Fastest SD Cards / The Current Top 9
These are the current fastest SD cards I’ve come across so far in my independent speed tests:
- Kingston Canvas React Plus V90 UHS-II
- Angelbird AV Pro SD MK2 V90 UHS-II
- ProGrade Digital V90 UHS-II
- Sony SF-G U3 UHS-II
- Lexar Professional 2000x U3 UHS-II
- Sony TOUGH-G SF-G(T) V90 UHS-II
- Toshiba Exceria Pro U3 UHS-II
- Transcend 700s V90 UHS-II
- SanDisk Extreme PRO U3 UHS-II
These SD cards are ranked by tested sequential write speed results. That’s the measure that’s most relevant to recording 4K, 8K, and high-bitrate video as well as fast photo burst modes. You can find more details below about each of these cards, as well as more information about how these tests were conducted.
Top 9 Fastest SD Cards Tested: Deeper Dive
Here’s some more detailed information on the top-ranking fastest SD cards I’ve tested. You can find the full list of tested cards in the table below.
Kingston Canvas React Plus V90 UHS-II SD Card
- Ultimate speeds to support professional camera use — Transfer speeds up to 300MB/s and recording speeds...
- UHS-II standard for reliable high-resolution photography and video recording — Capture 4K and 8K...
I’ve been using Kingston memory cards on and off for a long time and have always found them reliable and cost-effective. But this is the first card of theirs that I’ve used that is genuinely fast. And it’s very, very quick. With the Canvas React Plus lineup, they’re aiming for shooters of 4K and 8K video. And with their deep experience in producing memory cards, they seem to have nailed it.
The Canvas React Plus is available in sizes from 32GB to 256GB and comes with a UHS-II USB card reader.
Something to watch for is that there’s also a Canvas Go! and a Canvas Select Plus, both of which are slower than this card. The fast one is the Canvas React Plus and is rated for up to 300MB/s read speed.
Angelbird AV Pro SD MK2 V90 UHS-II SD Card
Angelbird is an Austrian company that focuses on flash memory storage for the pro end of the market, with an emphasis on cameras and devices with the highest bitrate recording. They deliberately aim for smaller production runs, but their SD cards have started becoming more widely available lately.
This card, model AV Pro SD MK2 V90, is currently their fastest SD card; they also have a slightly slower V60 version.
I was tipped off to this card by Panasonic GH5 and Fujifilm XT-4 shooters, cameras that both have very high bitrate recording modes. This is the first Angelbird card I’ve tested, and it immediately jumped to the top spot.
It’s rated for up to 280MB/s sequential write and 300MB/s sequential read (and sustained write speed of 260 MB/s and sustained read speed of 280 MB/s). It’s available in 256GB, 128GB, and 64GB sizes and comes with a 3-year limited warranty. And it’s has a UHS-II interface.
One small but nice touch is that the cards are sticker-free. So the information is printed directly on the card rather than a sticker label. That eliminates the risk of a sticker’s adhesive softening when the card gets hot at high data transfer speeds and gumming up the camera’s card slot. It’s a small thing, but a thoughtful one.
ProGrade Digital V90 UHS-II SD Card
- TURN YOUR PASSION INTO PROFIT – CALLING ALL VLOGGERS, INFLUENCERS, FILMMAKERS, PHOTOGRAPHERS &...
- LIGHTING FAST 250MB/s WRITE SPEED – INSTANTLY SAVE high resolution recordings to your device, ALL WHILE...
Model: PGSD64GBCJNA / PGSD128GBCJNA / PGSD256GBCJNA
ProGrade Digital is a new player in memory cards, but it has been created by a team with very deep experience in the industry. They’re focusing on high-end cards with an emphasis on cards geared towards top-shelf cameras and professional use. In other words, fast and reliable.
ProGrade Digital doesn’t have the marketing budget of the big brands, the cards come in bare-bones packaging, and the brand isn’t all that well known yet, but I’m impressed with what I’ve seen so far. This is now the card I’m using in my primary camera, and I’ve had a good experience with their other cards that I’ve tried (including the V60 version and their microSD card).
This card is the one with the V90 rating, and it’s available in 64GB, 128GB, and 256GB versions. There’s also a V60 version which isn’t quite as quick as this one but still has very high performance.
Sony SF-G U3 UHS-II SD Card
- In UHS-II devices, up to 300MB/s transfer speed and up to 299MB/s write speed
- Uhs-ii reader (mrw-s1) is needed to realize transfer speed
Model numbers: SF-G32 / SF-G64 / SF-G128
This card from Sony held the top spot in my speed tests for quite some time until it was pipped by the ProGrade Digital one. It’s rated for 299MB/s sequential write and 300MB/s sequential read, and its speed in my tests was top rate. It comes in 32GB, 64GB, and 128GB versions. Sony also has its M-series, which are a little slower but still very good cards.
It comes with a link to file recovery software and a 5-year limited warranty. It doesn’t come with a card reader.
Lexar Professional 2000x U3 UHS-II SD Card
- High-speed performance leverages UHS-II technology (U3) for a read transfer speed up to 2000x (300MB/s)
- Captures high-quality images and extended lengths of stunning 1080p full-HD, 3D, and 4K video with a DSLR...
Model No. LSD64GCRBNA2000R
Lexar has been one of the big, established players in memory cards for a long time now. But in recent years, they’ve had some corporate upheaval and a change of ownership. That seemed to disrupt the production and supply of their cards for a while. But that seems to be mostly rectified by now, and their cards are now readily available at many retailers.
With a UHS-II bus and a speed class of U3, Lexar rates this one for a read speed of up to 300 MB/s (or 2000x) but, as usual, doesn’t publish a write speed other than “write speeds slower.” But this card boasts impressive sequential write speed as well. It’s in the Lexar Professional line and comes in 32GB, 64GB, and 128GB versions.
This one also comes with its own USB thumb drive card reader, which also happens to be one of the fastest SD readers I’ve come across yet.
Sony TOUGH-G SFG-(T) V90 UHS-II SD Card
- Tough specs: world's first one-piece molded construction with high hardness materials have resulted in...
- Ribless, no write protection switch design: world's first ribless, no write protection switch design6...
Model No. SF-G(T)
This is a newer model than the other Sony card listed above and is now much more widely available in stores. And like the other card, it’s very quick in the kinds of reading and writing that matter for recording video and shooting burst and high-resolution photos. It’s rated for a sequential write speed of 299MB/s and a sequential read speed of 300MB/s.
They’re marketing this card as both fast and tough. The “tough” part comes in with some extra design elements aiming to make it more rugged, such as using a one-piece molded structure, getting rid of the ribs on the connector and the write-protect switch, and claiming that it’s “18 times more resistant to bending than conventional SD cards.” This all sounds impressive, but the focus of these tests is speed, and the good news is that the rugged design doesn’t appear to have led to any compromise in speed. So it appears to be a win-win.
It’s a UHS-II card that carries a V90 rating. It comes in 32GB, 64GB, and 128GB sizes (for now, there aren’t 256GB or 512GB versions).
Toshiba Exceria Pro U3 UHS-II SD Card
- Achieve exceptional speed-up to 260 MB/s read speed and 240 MB/s write speed.
- Transfer 1,000 photos in only one-fifth the time needed by class 4 SD cards
Model No. N101
Check current price & availability at: Amazon
Toshiba isn’t often one of the first brands that come to mind with memory cards, but they’ve long been one of the best hard drive and SSD manufacturers around, so they come with very, very deep experience in flash memory. And while they’ve had some impressive cards in their Exceria Pro line for a while, they don’t seem to have really pushed hard on the memory card direction, and their cards aren’t always easy to find in stores.
Performance-wise, I found this card to be very close to the Lexar 2000x. But it falls short regarding value—it’s consistently significantly more expensive than some of the other lines, which presumably goes hand-in-hand with the relative scarcity in availability.
It comes in 16GB, 32GB, 64GB, and 128GB versions.
Transcend 700S V90 UHS-II SD Card
- Compliant with UHS-II U3 and V90 standards
- Sequential Read/Write: 285 MB/s Read; 180 MB/s write
Transcend doesn’t have the market presence of some other brands, but they’ve been making very good cards for a long time now. This card is quick, but one potential negative I’ve come across is that so far is that I’ve only seen it available in 64GB and 32GB sizes.
SanDisk Extreme PRO U3 UHS-II SD Card
- Bundle includes (1) SanDisk SD Extreme Pro UHS-II memory card and (1) Everything But Stromboli (TM) 3.0...
- Critical for continuous burst shooting on your Sony Alpha a7 III, a7r III, a9 Mirrorless Cameras.
Model No. SDSDXPK
The SanDisk Extreme Pro badge is for SanDisk’s top-of-the-line range. These are reliably solid performers from a top-notch flash memory brand. SanDisk tends to refresh their product line much more frequently than many of their competitors, but they reuse the same series names (e.g., Extreme Pro). Performance is typically very consistent from model to model, so they’re a very good, reliable option. It comes in 32GB, 64GB, and 128GB versions.
Does the Speed of SD Cards Matter?
For several years now, I’ve been trying to buy and test as many SD and microSD cards as I can. I’ve been posting the results since 2017. This post is based on the results of the numerous SD card tests I’ve run since; you can find my tests for the fastest microSD cards here. This page covers SDXC and SDHC cards, including UHS-I and UHS-II interface cards.
My focus here is on SD cards that are well-suited to use in cameras for recording high-bitrate, high-resolution video (4K, 5K, and 8K, for example), high-resolution photos, and burst sequences of photos. So I’m most concerned with sequential write speed rather than the types of write speed that some other applications need, such as gaming and computing devices.
The top cameras on the market now have capabilities that can demand a lot from the memory card. It’s becoming routine for these high-end consumer cameras to be able to record video at very high bitrates around 400 Mb/s. Even mid-range and compact cameras are able to record at bitrates of up to and over 100 Mb/s when shooting 4K and 8K video. That opens the possibility of some very high-quality video footage. But it’s one thing for the camera to be able to shoot at those bitrates; the other piece of the puzzle is that you’ll need a memory card that can keep up. With a card that’s too slow, you run the risk of the recording stopping unexpectedly, dropouts, or even the camera freezing up.
And, to be honest, buying an SD card that’s fast enough should be easier. The SD Association, the non-profit organization that controls the specifications that SD cards must abide by, has helpfully created a rating system to categorize cards according to video recording speed. It’s designed to make it easier for the consumer to see what’s what. Or rather, there are several rating systems now, as older versions have become outdated. And even within the bands of those ratings, there’s a lot of room for variation. Making it even more complicated, when memory card manufacturers advertise their cards’ speeds, the first and largest number they typically use refers to the sequential read speed. That refers to how quickly data can be downloaded from the card. But when recording video or burst mode photos, what you want to look at is the sequential write speed. That’s how fast you can get data on to the card. It’s often not as clear as it could be; more manufacturers are starting to include it on the packaging, but it’s by no means universal yet.
Which is why I go to the effort of buying and testing the SD cards for myself and sharing the results. My hope is to provide more information that photographers and videographers can use in deciding which memory cards will the best for a particular camera in real-world shooting conditions. In short: in ranking the cards here, I’m focusing on the sequential write speeds. I’m also basing them on my own tests rather than the claims of the manufacturers.1
But it’s not always true that the fastest card is necessarily the best card for what you need. Price and availability matter too. And then there’s the important issue of whether your camera can take full advantage of the card’s speed. In most cases, you can safely put a very fast card in a slower camera, but it doesn’t always work that you’ll get many benefits from the fastest card in the camera. It depends on what you’re putting it in. To take advantage of what UHS-II cards can do, for instance, you’ll need a camera or reader that’s compatible with UHS-II. If it’s not, the card will still work—they’re designed to be backward compatible in nearly all cases—but you won’t get the highest speeds the card is capable of. One place you might see some benefit, though, is when you go to download the photos from the card to your computer using a card reader. Most of the time, what you need isn’t necessarily the fastest SD card that you can find but rather one that’s fast enough for your camera and workflow. And that’s cost-effective. And that you can find at retailers.
Detailed SD Speed Test Results
These are sorted by default by descending sequential write speed, but you can click on the column headers to sort by other criteria or use the search bar to filter by brand, etc. You can also scroll the table right to get the other columns.
|Brand||Model #||Class||UHS||Tested Write / Seq||Tested Read / Seq||Tested Read / But||Tested Write / Ran||Rated Read MB/s*||Rated Write MB/s*|
|Kingston||Canvas React Plus (MLPR2 )||V90||UHS-II||274.0||291.5||265.4||9.0||300||260|
|Angelbird||AV Pro SD MK2 V90||V90||UHS-II||272.5||295.5||270.1||12.7||300||280|
|Lexar||Professional 2000x LSD32GCRBNA2000R||U3||UHS-II||241.4||278.0||248.3||180.5||300||-|
|Toshiba||Exceria Pro N101||U3||UHS-II||231.7||254.4||236.9||231.7||141.5||-|
|SanDisk||Extreme Pro SDSDXP||U3||UHS-II||196.8||257.7||222.7||7.2||280||250|
|SanDisk||Extreme Pro (SDSDXPK)||U3||UHS-II||105.6||230.0||184.0||25.8||300||260|
|Delkin Devices||Power (DESD2000)||V90||UHS-II||105.5||229.0||182.4||83.2||300||100|
|SanDisk||SanDisk Extreme Pro (SDSDXXG)||U3||UHS-I||90.5||98.8||88.5||78.5||95||90|
|SanDisk||Extreme Pro SDSDXPA||U3||UHS-I||89.2||94.5||85.3||77.2||95||90|
|Lexar||Professional 1000x LSD32GCRBNA1000||U3||UHS-II||82.2||156.3||141.6||58.2||150||-|
|Delkin Devices||Advantage (DDSDW633)||V30||UHS-I||75.7||99.0||91.6||52.1||100||80|
|Delkin Devices||Select (DDSDR266)||V10||UHS-I||70.3||98.7||87.4||56.7||40||20|
|Kingston||Canvas Go! (SDG)||V30||UHS-I||69.8||97.7||95.4||64.4||90||45|
|SanDisk||Extreme PLUS SDSDXSF||U3||UHS-I||64.6||88.7||85.6||59.6||90||60|
|Delkin Devices||Prime (DDSDB1900)||V60||UHS-II||60.3||211.4||171.1||12.0||300||100|
|PNY||Elite Performance P-SDX128U395-GE||U3||UHS-I||51.5||95.2||90.2||32.6||95||-|
|Lexar||Professional 633x LSD64GCBNL633||U3||UHS-I||40.1||79.4||75.7||24.2||95||-|
|Micro Center||Extreme Speed||U1||UHS-I||25.9||97.1||95.3||25.8||60||10|
This obviously doesn’t include every SD card available. It’s a growing list that’s a work-in-progress, and I’m adding new cards as I get the opportunity to test them. I’m putting the priority on cards that are readily available and from major manufacturers and that seem likely to rate near the top of the pack in terms of speed. If you have one you’re interested in that’s not on the list, by all means, drop a note in the comments. I can’t promise I can get to every card, but I can try.
Real-World SD Card Speed Tests
In conducting these tests, my objective is to test the performance that we can realistically expect using off-the-shelf hardware.
To be clear, there are two things I am not trying to do. I’m not trying to replicate the manufacturers’ lab tests. And I’m not trying to play gotcha and test whether the speed ratings the manufacturers claim are accurate. There are, after all, several things that can affect the speeds you can get out of cards in practice.
What I am trying to do is find out which cards perform best in real-world conditions and how they compare relative to each other. Because those are the things that matter to me when I’m trying to decide which card to buy. In short, I’m looking for practical speeds, not theoretical speeds, and whether one card is faster than another.
So I’m using a real-world computer setup, not some high-end custom rig optimized to squeeze every last bit of bus transfer speed but not much good for actually processing photos and videos. There are dedicated hardware devices that exist only to test the speed of memory cards. Those are ridiculously expensive (yes, I looked into getting on at one point) and not useful for any other purpose. Instead, I’m using readily available standard hardware that photographers might have on hand.
For the reader, I’m using a ProGrade Digital USB 3.2 Gen. 2.0 Dual-Slot UHS-II reader. It’s connected with a ProGrade Digital USB 3.2 Gen 2 Super Speed+ certified cabled via the Mac’s USB-C port. After extensive testing, I’ve found that this reader gives me the most reliable and consistent results, especially with the newer, faster cards.
For the software, I’m using the benchmarking suite in Digital Media Doctor by LC-Technology. All cards were new or near-new and freshly formatted with the SD Association’s official app before running the tests. I’m running 5GB datastreams for all the read and write operations. Because results often vary slightly between each test, I’m running each set of tests five times and averaging the results.
For the computer, I’m using an iMac Retina 5K 2019 with an internal SSD.2 There are faster, more powerful computers that might squeeze out higher transfer rates, but this provides a useful real-world platform that is widely used and available.
Reliability & Ruggedness
These tests do not address the issues of reliability or ruggedness. While flash memory is generally quite stable, in part because there are no moving parts, memory cards can fail. When choosing which cards to use myself, speed is one factor, but I also generally favor cards from well-established brands. And for normal use, those typically offer excellent performance.
But if you’re choosing a memory card for what amounts to near-constant writing—such as with a dashcam or security cam that is constantly being overwritten—you might be better off in the long run with one of the specialized high-endurance cards that some brands offer. They typically aren’t at the top of the speed charts, but they add extra peace of mind that the card should be able to tolerate very high numbers of write cycles.
I’m also not testing the physical ruggedness of the card. That is, I’m not trying my best to crunch them or drown them. Most SD cards now include claims of being waterproof, dustproof, freezeproof, and crushproof. Some, like Sony’s TOUGH line, take things the extra mile. But it’s just not something I have either the inclination or the means to test.
The Notes / Definitions
Like everything else in electronics, memory cards come with a dense cloud of jargon. Here are some brief explanations of what the various bits and pieces mean.
Speed Ratings: Megabytes vs. Megabits
All speed ratings I’m using here are in MB/s (megabytes per second), which is not to be confused with Mb/s (megabits per second). Memory card manufacturers usually measure the speed of their cards in megabytes per second, or MB/s (or MBps, both with an uppercase “B”). But video recording bitrates are usually measured in megabits per second, or Mb/s (or Mbps, with a lowercase “b”). They’re not the same thing. There are 8 bits in a byte, so to get from megabits per second to megabytes per second, you multiply by 8. So 80MB/s is the same as 640Mb/s. Here’s a handy conversion calculator.
X Rating vs MB/s. Some manufacturers use a more cryptic x rating in place of MB/s. Lexar, in particular, has long used this system. It comes from the old way of measuring the speed of CD-ROM drives when the standard speed of a CD-ROM drive was 150KB/s. Each x, therefore, equals 150KB/s.
Here’s a quick cheat sheet for converting some of the common x ratings to MB/s:
SDHC vs. SDXC vs. SDUC
One of the several codes you’ll see on SD cards is either SDHC or SDXC. This isn’t a performance rating, as such. It refers to the filesystem used on it, either FAT32 (SDHC) or exFAT (SDXC). The SD Association has specified that cards that have a storage capacity of 32GB or smaller will be formatted as FAT32, while those 64GB and larger will be formatted with exFAT. The result is that all the cards between 4GB and 32GB will be marked with SDHC, while cards 64GB to 512GB will have SDXC.3 There’s also a newer SDUC specification, but it’s unlikely that you’ll come across those in stores just yet.
SDHC (Secure Digital High Capacity) is a design specification that refers to SD cards that are between 4GB and 32GB in capacity and formatted with the FAT32 filesystem. FAT32 supports individual files up to a maximum of 4GB (which is also why many cameras break up their video files into chunks that are 4GB or less).
SDXC (Secure Digital eXtended Capacity) refers to SD cards with a capacity larger than 32GB. They’re formatted in the exFAT filesystem.
SDUC The SD Association has also created a newer specification known as SDUC, for SD Ultra Capacity. It has its own host technology, protocols, and drivers, but in terms of card storage capacity, it’s designed to cover cards ranging from 2TB up to 128TB. SDUC cards will only work with devices that have SDUC compatibility specifically included, so you can’t just put an SDUC card in a camera that doesn’t specifically support SDUC. But you won’t find any of those cards in the wild just yet, so, for now, at least, you don’t really need to be concerned about accidentally getting one of those.
Technically, it’s possible to use a computer to format, say, a 32GB microSD card with exFAT or a 128GB card with FAT32. But doing so goes against the SD Association specifications, can cause problems in some cameras, and they’ll be overwritten to the appropriate standard next time you format the card in the camera. In general, I don’t recommend it. That said, if you really want to do it, I’ve put together a guide to using the official SD card formatter.
SD Card Speed Classes
SD cards are given a speed class rating that refers to its category for writing data, with each category describing a real-world video recording use. These apply the same to SDHC and SDXC cards. The most recent types of speed class start with a U or V, as in U3 or V90. Some cards might carry both a U and V rating (and a Class 10 as well, for that matter), in which case you can focus on the higher, which would be the V rating.
Where things get a little complicated, though, is that these speed ratings don’t necessarily reflect the absolute speed of the card. Put another way, a card that has a V30 rating isn’t necessarily faster than one that has a U3 rating. That’s because to display the rating on the card, the manufacturers have to have their cards certified for that rating. It also involves revising packaging and marketing materials, which is an expensive process. So not every manufacturer will go to that trouble and expense right away. The upshot is that it’s not as simple as just looking at a card with a V30 or even V60 rating and knowing that it’s faster than one that only carries a U3 rating. It might be, but the rating system doesn’t work quite that way. You can see evidence of that in the speed test results on this page, with some cards with a lower speed rating being faster in testing than ones that display a higher speed rating on the packaging.
V90. The V-class (for video) is a new designation created for cards that are designed to work with the speeds required for 4K and 8K video. The SD Association added some lower numbers to make them backward compatible with the older class designations (e.g., Class 10 and Class 6), but the most important ones are V30 and above.
Memory cards in the V90 class are rated to support a minimum sequential write speed of 90MB/sec. Their primary market is for cameras that shoot 8K video, and for now, those are pretty rare, but the class provides room to grow, as it were.
V60 is applied to cards that support a minimum sequential write speed of 60MB/sec. They’re aimed primarily at cameras that record 4K and 8K video. Some of the newer cameras that record with ultra-high bitrates, like the Panasonic GH5, require V60 or above. With other 4K cameras that record at lower bitrates, you might get away with a V30 card.
V30 is applied to cards that support a minimum sequential write speed of 30MB/sec. These are designed to support at least full HD video and some 4K video cameras.
U3 is designed to support 4K video recording at a sustained video capture rate of 30MB/s. This class overlaps with the newer V30 class.
U1 is designed to support real-time broadcasts and HD video (720p and 1080p) with a minimum serial write speed of 10 MB/s. This overlaps with the newer V10 class.
Class 10 is designed to support 1080p recording at a minimum (but again, not at all framerates) with a minimum serial write speed of 10 MB/s.
Classes 2, 4, and 6. Class 2 supports SD video recording with a minimum serial write speed of 2MB/s. Classes 4 and 6 are designed to support from 720p and 1080p video (but not all framerates) with a minimum serial write speed of 4 MB/s and 6 MB/s, respectively. Most newer cameras need cards faster than these, so memory cards in these speed classes aren’t as commonly available now.
For practical purposes, the most common currently are Class 10, U1, U3, V30, V60, and V90, with V60 and V90 being the current fastest classes. It is technically still possible to find older, slower cards that are Class 2, 4, or 6, but most modern cameras are likely to work better with at least Class 10 cards, especially for recording video.
The SD Association is regularly tweaking specifications to allow for faster and better performance from SD and microSD cards. In May 2020, they released an SD Express 8.0 specification with a dramatic increase in potential transfer speeds, allowing for transfer speeds of up to nearly 4000MB/second. It’s designed to be available on SHDC, SDXC, and SDUC cards. But for now, it’s just a spec and hasn’t yet been implemented in any consumer cards or devices.
SD vs CFexpress A
There are new types of memory cards developed by the CompactFlash Association known as CFexpress. There are currently three types of CFexpress cards: CFexpress Type A, CFexpress Type B, and CFexpress Type C. Each type is a different physical size and has its own characteristics.
CFexpress A cards are the same physical dimensions and pin layout as SD cards. So a CFexpress A card will fit in an SD slot, and vice versa. CFexpress A cards are also much faster and more expensive than SD cards.
But in most devices, just because the cards will physically fit doesn’t mean it’s compatible. The device has to be specifically compatible with CFexpress A for those cards to work.
What is the A Rating (e.g., A1 and A2)?
You might have seen A1 and A2 ratings on some of the new cards and wondered what that is. The A1 and A2 ratings are part of a new type of speed specification that’s relevant for running apps from the memory card. The A rating is a separate specification, not one in the same sequence. So it’s possible for a card to have both A1 and V30 ratings, for example.
Up to this point, the primary market for memory cards has been for storing media like videos or photos. But increasingly, devices can run apps directly from a memory card. And that requires a different type of interaction with the space on the memory card—specifically, random read and write speeds and small chunks of data are placed wherever on the card there’s space for them.
So the new A specification (for App Performance) incorporates the random read/write speed. If you’re buying a memory card for a camera, it’s not especially relevant because what’s requires on those is sequential speed. So if you’re recording video (or shooting photos), the speed classes you want to look for are the ones starting with V (e.g., V30 or V60) or U (U1 or U3). But if you’re buying a memory card for a gaming device or smartphone or some other kind of device that runs apps and uses SD or microSD memory cards, the A rating is designed as a guide for what cards are best suited to that kind of use.
UHS-I vs. UHS-II
Newer SDHC and SDXC cards have a feature called ultra-high-speed bus, which refers to the interface. So far, there is UHS-I and UHS-II. UHS-I supports a maximum bus speed of 104Mb/s, while UHS-II supports up to 312MB/s. The spec for UHS-III, maxing out at 624MB/s, has been announced, but so far, I’ve not seen any implementations of it in the wild.
The product labeling for cards with this technology will have either UHS-I or UHS-II, or sometimes just I or II. Technically, it should be Roman numerals, but you’ll sometimes see it listed with a number 1, like UHS-1, even by some manufacturers.
You can also tell them apart by looking at the cards themselves. UHS-I cards have a single row of pins on the back. UHS-II has two rows. In this example, both of these are SanDisk Extreme Pro cards, just different generations.
As with many aspects of memory cards, it’s not cut and dried. UHS-II (and UHS-III) allows for higher potential speeds, but in practice, there’s no guarantee that a UHS-II SD card will be faster than a UHS-I SD card, because there are other factors that come into play.
One is the design of the card. Another is that it matters what you’re putting the card in. It’s important to note that taking advantage of the potential speed increases of UHS-II requires that both the card and the host (e.g., card reader or camera) support it. Putting a UHS-II card in a camera or host that only supports UHS-I will result in it falling back to UHS-I speeds. Ditto on putting a UHS-I card in a UHS-II-enabled device. (All of the tests here are done with UHS-II readers and hardware.)
SD vs microSD vs CompactFlash vs CFAST 2.0 vs XQD 2.0
Some cameras come with multiple memory card slots, so you can choose which to use (or use both).
The speed of SD cards has come along in leaps and bounds in the past few years. At the moment, the fastest SD cards are faster than the fastest microSD cards, faster than the fastest CompactFlash cards4, and slower than CFAST 2.0 and XQD 2.0 cards.
General Recommendations for Using SD Cards
Here are some general tips for buying and using SD cards.
- There are counterfeit memory cards in the marketplace, especially when you’re buying online. Buying from a reputable retailer helps minimize the risk of getting a fake.
- SD cards are remarkably strong and rugged and are advertised as waterproof, crushproof, freezeproof, and dustproof, but they’re not completely indestructible. And being so small, they’re pretty easy to misplace. And losing all your photos or videos is a high price to pay for seeing just how far you can push it. They’re also not designed for long-term archival storage of photos and videos. It’s good practice to download the data as soon as practical and get it backed up securely.
- Memory cards are complicated electronic products. A small percentage of electronic products end up being faulty from the manufacturing process. So it’s good practice to test your card before using it in a mission-critical application. Better yet, have a spare (or, better yet, spares) on hand as a backup.
- Always format the card in the camera rather than with your computer, and do it fairly regularly. This keeps the memory card’s filesystem set up the way the camera wants it and reduces the risk of formatting problems.
- It’s always best practice to format memory cards in the camera you’re going to use them in, but if that’s not possible or not what you want to do, you can also format cards using a computer. But there are some things to know when formatting SD cards to minimize the risks of your camera having problems with them. So I’ve put together guides on how to format SD cards on Mac and how to use the free SD Card Formatter app for Windows or Mac.
- If you happen to be using the SD cards in a device that runs apps, like a gaming device, the random read/write speed is more important; see the section below about the A rating. ↩
- Some earlier tests were done on an older computer, an iMac 5K Retina late-2014. ↩
- It is technically possible to use a computer to mix and match filesystems and memory card sizes. For instance, you can format a 16GB with exFAT or a 64GB card with FAT32. But that’s rarely a good idea because it can cause issues when you go to use them in a camera or other device. Some cameras check the filesystem against the storage capacity and throw an error if it doesn’t square with what it expects to see. ↩
- This is true of the cards themselves, but some devices can read much more quickly from CompactFlash slots than SD slots. ↩
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