If you’re using a microSD card in something like a GoPro or other small camera or camcorder that records high-resolution video, speed matters. And just like with their bigger siblings, SD and Compact Flash cards, the speed of microSD cards vary widely from card to card.
The even-numbered class designations for SD and microSD cards, like Class 6 or Class 10, were supposed to provide an easy way to see if a card was fast enough for a particular use. And they did . . . for a while. But the capabilities of the newest cameras need something better than just Class 10. Most Class 10 cards won’t work well in the newest GoPro HERO4 Black or new HERO5 Black, for instance.
So you really need to look further to the read and write speeds. Of these, the write speed is by far the most important for most camera uses. That tells you how fast you can get data on to the card. That doesn’t tend to matter as much when using microSD cards in smartphones or GPS units, but it does matter for cameras when you’re shooting in burst mode or recording high definition 4K video or super fast framerates. The read speed, which is often used in marketing, tells you how fast you can get data off the card. With the speed tests and rankings below, I’m focusing on the write speeds and basing them on my own independent real-world testing.
But manufacturers don’t always make it easy to see what the read and write speeds are. Names like “Ultimate,” “Extreme,” and “Elite Performance” aren’t particularly helpful, especially when speeds are improving so rapidly and manufacturers are recycling the same card names with newer cards with different specs. And some manufacturers advertise speeds measured in megabytes per second, while others use more cryptic multipliers like 633x, making it hard to compare.
So I’ve been putting some of the microSD cards that are most readily available to the test. My focus here is on their speed for recording video and burst mode photos in the current generations of action cams like the GoPro HERO5 Black.
Current Top 5
Here are the ones that fill the top 5 spots in my tests of sequential write speed, the one that’s important for high-resolution video. These three are more than fast enough for the GoPro HERO5 Black and the GoPro HERO4 Black.
SanDisk Extreme PLUS
Model No. SDSQXSG
Sandisk uses a three-part model numbering system in the format SDSQXSG-064G-ANCMA. In this example, SDSQXSG is the model general, 064G refers to the amount of memory, and the last 5 characters are used by the marketing department for different parts of the world but the cards are otherwise the same. So the first part is the crucial part if you’re looking to see which model the card is.
SanDisk Extreme PRO
Model No. SDSDQXP
SanDisk has released a newer version of this card (model SDSQXPJ) in 64GB and 128GB sizes. I’ll be testing it very shortly and updating this list as necessary.
SanDisk Extreme PLUS
Model No. SDSQXWG
This new version of the Extreme PLUS is rated for the new V30 speed class, meaning that it’s rated for a sustained write speed of at least 30MB/s. The class was added to denote cards suitable for 4K and 360° video. V30 might also work for some 8K footage, but there are faster classes, V60 and V90 that more comfortable accommodate those speed requirements.
Model No. MB-MD32DA/AM
Samsung has two cards with very similar specs. This one, the Pro+ is rated for U3.
Model No. MB-MG32DA/AM
Available at: Amazon
This one is rated for U1 rather than the U3 of the Pro+, but in practice there’s not a lot of difference in speed.
Benchmark Speed Test Results
Below is the full list. 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 or model number. You can also scroll the table right to get the other columns.
|Brand||Model #||Speed Class||UHS||Tested Write / Seq||Tested Read / Seq||Tested Read / But||Tested Write / Ran||Rated Read MB/s||Rated Write MB/s|
|SanDisk||Extreme Plus (SDSQXSG-032G-GN6MA)||U3||UHS-I||87.8||86.0||83||80.8||95||90|
|SanDisk||Extreme Pro (SDSDQXP-064G-G46A)||U3||UHS-I||87.6||85.2||82.4||80.3||95||90|
|SanDisk||Extreme PLUS (SDSQXWG-064G-ANCMA)||V30||UHS-I||87.2||91.0||90.3||85.3||95||90|
|Transcend||Ultimate 633x (TS32GUSDU3)||U3||UHS-I||73.7||91.1||87.7||18.2||95||85|
|SanDisk||Extreme PRO (SDSQXPJ-064G-ANCM3)||U3||UHS-II||64.9||211.5||205.3||9.3||275||100|
|Silicon Power||Superior Pro (SP032GBSTHDU3V20SP)||U3||UHS-I||55.1||89.1||81.8||2.6||90||80|
|SanDisk||Ultra Plus (SDSQUSC-032G-ANCIA)||C10||UHS-I||50.3||92.2||88.7||12.9||80|
Obviously, this doesn’t include every microSD card available. It’s a growing list that I aim to update regularly as new cards are released and become readily available. If you have one you think should be added to the list, let me know.
Real-World Speed Tests
In real-world use, a range of technical factors in the camera and its transfer hardware and software can prevent you from hitting the speed numbers on the card’s packaging. What I’m focusing on here is real-world uses, not scientific lab results that can’t be replicated in practical use.
In conducting these tests, my objective is to test the performance that we can realistically expect using off-the-shelf hardware.
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 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.
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 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 Lexar LRWM05U-7000 USB thumb reader. It’s one of the two options that comes with the Lexar 1800x microSD cards. I’ve found it to be the fastest of the readers that are readily available—faster even than my Lexar Professional Workflow microSD reader—and because it connects directly to the computer’s USB port it eliminates any potential issues with cables or external card reader interfaces. It’s connected via USB 3.0 and is UHS-II compatible.
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. Results can vary between each test. So I’m running each set of tests three times and averaging the results.
For the computer, I’m using an iMac Retina 5K late-2014 with an internal SSD. 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.
The Notes / Definitions
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). Megabits per second is more commonly used by cameras and in recording video. There are 8 bits in a byte, so to get from megabits per second to megabytes per second you multiple 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
The codes microSDHC and microSDXC are useful in determining what size card will work in your device. If your device specs say that it only works with microSDHC, then you’ll want a card that’s 32GB or smaller.
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.
SDXC (Secure Digital eXtended Capacity) refers to SD cards with a capacity larger than 32GB and with a maximum theoretical limit of 2TB. They’re formatted in the exFAT filesystem.
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.
Class 2 supports SD video recording with a minimum serial write speed of 2 MB/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.
Class 10 is designed to support 1080p recording at minimum (but again, not at all framerates) with a minimum serial write speed of 10 MB/s. You’ll often see it marketed as “full HD”, but that’s pretty outdated now. What “full HD” means in this context is 1080HD video, which is no longer a cutting edge HD video mode.
U1 is designed to support real-time broadcasts and HD video (720p and 1080p) with a minimum serial write speed of 10 MB/s.
U3 is designed to support 4K video recording at a sustained video capture rate of 30MB/s.
For practical purposes, the most common currently are Class 10, U1, and U3, with U3 being the current fastest class. 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.
UHS-I vs UHS-II
Newer microSDHC and microSDXC cards have a feature called ultra high-speed bus, which refers to the interface. So far, there is UHS-I and UHS-II.
UHS-II is the newer, and potentially faster, system but adoption is still not widespread. And a UHS-II isn’t necessarily guaranteed to be faster than every UHS-I card in practice, as you can see from the test results above. The UHS-I category refers a type of interface that has a potential maximum speed of 104MB/sec.
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 list 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.
But it’s important to note that taking advantage of the potential speed increases of UHS-II requires that both the card and the host (eg. card reader or camera) support it. Using a UHS-II card in a camera or host that only supports UHS-I will result in it falling back to UHS-I speeds. Put another way, if you use a UHS-II card in a card reader or device that’s only rated for UHS-I, you’ll only get a maximum potential of UHS-I.
- There are counterfeit memory cards out there. Buying from a reputable retailer helps minimize the risk of getting a fake.
- 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 spare/s as backup.
- Memory cards are not designed for long-term archival storage of photos and video. It’s good practice to download the data as soon as practical and get it backed up securely.
- Format the card in the camera rather than with your computer. It reduces the risk of formatting problems.