A memory card is an essential accessory to make your camera work, but the Canon PowerShot SX420 doesn’t actually come with one in the box.
While some retailers sell the camera in a bundle that includes a starter memory card, those bundled cards are notoriously small and cheap. They fill up incredibly quickly, especially if you are taking the camera’s massive 42x optical zoom on a long vacation.
If you’re looking to pick up a reliable, high-capacity memory card for your SX420, it is easy to get overwhelmed by all the cryptic speed classes and technical codes printed on modern SD cards. I’ve been buying, testing, and formatting SD cards for years, and the good news is that this specific camera is incredibly forgiving.
Here are my practical recommendations for the best SD cards for the Canon PowerShot SX420 so you can spend less time decoding spec sheets and more time out shooting.
My top recommended SD cards for the SX420
If you just want to grab a card and go, any of the options below will work perfectly in the SX420. They easily handle the camera’s video requirements, have a fantastic track record for reliability, and are highly cost-effective.
- Type: SDXC / SDHC
- Video Speed Class: V30
- UHS Bus Interface Type: UHS-I
- Maximum Read Speed: 230 MB/s
- Storage Capacities: 32GB, 64GB, 128GB, 256GB, 512GB
Check current price and availability at:
- Video Speed Class: V30
- UHS Bus Interface Type: UHS-I
- Maximum Read Speed: 150 MB/s
- Storage Capacities: 64GB, 128GB, 256GB
Check current price and availability at:
- Type: SDXC
- Video Speed Class: V30
- UHS Bus Interface Type: UHS-I
- Maximum Read Speed: Up to 180 MB/s
- Storage Capacities: 128GB, 256GB, 512GB, 1TB
Check current price and availability at:
Recommendations checked: August 2026
Canon PowerShot SX420 SD Card Compatibility
To understand why those cards are the best fit, it helps to look at what the Canon PowerShot SX420 actually demands from its storage.
If you check the user manual, Canon is frustratingly vague, simply stating: “The following memory cards (commercially available) can be used, regardless of capacity: SD memory cards, SDHC memory cards, SDXC memory cards.”
In reality, your choice of card dictates how well the camera performs. A high-performance memory card isn’t going to magically improve your image quality, but a cheap, unbranded card that is too slow to keep up with the camera’s processor can cause frustrating issues like freezing, dropped video frames, or corrupted files.
Here is exactly what the SX420’s hardware requires.
Do you need a UHS-II card for the SX420?
No. The Canon PowerShot SX420 is built with a single UHS-I SD card slot.
UHS-I is the older, standard bus interface. Modern, premium cameras use UHS-II, which adds a second row of physical connection pins to the back of the card to achieve blazing-fast speeds. Because SD cards are fully backwards compatible, you can physically put a high-end UHS-II card into the SX420, and it will work just fine. However, the camera lacks the internal hardware to read that second row of pins, meaning your expensive UHS-II card will simply throttle down and operate at standard UHS-I speeds.
Save your money and stick to a high-quality UHS-I card.
What video speed class does the SX420 require?
The SX420 shoots video at a maximum resolution of 720p HD (at 25 fps). Compared to modern mirrorless cameras that shoot 4K or 8K video, 720p is a very low-resolution, low-bitrate format.
Because the camera isn’t writing massive amounts of video data to the card every second, you do not need to buy a premium V60 or V90 video-rated card. For the SX420, an SD card with a Class 10, U1, or V30 rating is more than fast enough to record smooth, uninterrupted video.
These cards are all rated V30 and work well in a very wide variety of cameras, with good versatility for shooting photos and 4K video.
My emphasis here is on cards that meet these criteria:
- They're fast enough for all the features of this camera.
- They're from a reputable and reliable brand, so you can count on them working well.
- They're readily available at major retailers, so you should be able to find them without much trouble.
- They're good value for money, so you're not paying too much for a card that is more than your camera can take full advantage of.
If you want to use a faster, fancier card, you can, but you won't see any extra benefit in doing so while you're operating the camera (but you might see some faster speeds when downloading the photos to a computer, depending on your computer and memory card reader combination). And, as always, I recommend buying from a major retailer to minimize the chances of getting burned with a counterfeit memory card.
SanDisk Extreme V30 UHS-I
- Type: SDXC / SDHC
- Video Speed Class: V30
- UHS Bus Interface Type: UHS-I
- Maximum Read Speed: 230 MB/s
- Storage Capacities: 32GB, 64GB, 128GB, 256GB, 512GB
Check current price and availability at:
SanDisk's Extreme range are good bets for many cameras, and that's true here too. SanDisk has faster ranges, like the Extreme Pro line, but this Extreme line is both quick enough for most cameras and usually less expensive than those faster cards.
One thing to note with SanDisk cards is that they recycle their model names. So you can find Extreme cards that are older and slower. You'll probably find those older versions work just fine — it really depends how far back you go. I've used many SanDisk Extreme cards over the years in many different cameras and have found them to be very reliable. They're also often good value, and you can sometimes find them sold in 2-packs (it's always good to have a spare on hand!).
Lexar High-Performance 800x PRO BLUE Series V30 UHS-I
- Video Speed Class: V30
- UHS Bus Interface Type: UHS-I
- Maximum Read Speed: 150 MB/s
- Storage Capacities: 64GB, 128GB, 256GB
Check current price and availability at:
The Lexar 800x Pro range is a relatively new model that replaces the old 633x cards that were mainstays of Lexar's SD cards for a long time. This newer V30 card is still a good combination of speed, reliability, and value, and you can often find them in multipacks to have spares on hand.
Delkin Devices ADVANTAGE V30 UHS-I SDXC (180 MB/s)
- Type: SDXC
- Video Speed Class: V30
- UHS Bus Interface Type: UHS-I
- Maximum Read Speed: Up to 180 MB/s
- Storage Capacities: 128GB, 256GB, 512GB, 1TB
Check current price and availability at:
Delkin Devices have recently come out with a range of new SD cards of varying speeds and specs. This is one of their mid-range cards that is rated for V30 video recording speeds. This newer version is rated for read speeds of up to 180 MB/s (the older version of the Advantage maxxed out at 90 MB/s).
Nextorage Classic V30 UHS-I SDXC Card
- Type: SDXC
- Video Speed Class: V30
- UHS Bus Interface Type: UHS-I
- Maximum Read Speed: Up to 200 MB/s
- Storage Capacities: 128GB, 256GB, 512GB
Check current price and availability at:
Japanese brand Nextorage makes excellent memory cards, although they're not always easy to find in stores in the US. But if you can find them, in my experience they're a very good bet. This is their basic (or "Classic") model, rated for V30.
Recommendations checked: August 2026
What is the maximum capacity SD card the SX420 can hold?
Because the SX420 is compatible with the SDXC standard, it can theoretically accept cards up to 2TB in size. Practically speaking, however, a 64GB or 128GB SDXC card is the perfect sweet spot for this camera.
Another factor working in your favor is that the SX420 only shoots JPEG photos; it does not shoot uncompressed RAW files. JPEG files are quite small, meaning you can fit a staggering amount of them onto a single card.
Canon has put together these estimates for how many 20-megapixel photos will fit on a standard memory card (you can find them on page 143 of the manual. These are based on an old 16GB card, so you can multiply them by the appropriate amount for larger cards (for instance, multiply by 4x for a 64GB card, or 8x for a 128GB card).
They’ve done the same for video capacities. Notice that a 16GB card will hold nearly an hour and a half of 720p HD video. A 64GB card will hold almost 6 hours.
How to format the memory card in the Canon SX420
When you buy a new SD card, you should always format it before using it for the first time. It is best practice to always format memory cards directly inside the camera you’ll be using them in, rather than on your computer.
Formatting the card in the SX420 sets up the exact folder hierarchy and database files the camera expects to see, which greatly reduces the risk of unexpected file errors later.1
On the Canon PowerShot SX420, you can find the format function here:
Settings (the yellow tools icon) > FormatFor day-to-day use, the standard formatting is all you need to clear the card and free up space.
If you’re actively trying to troubleshoot a memory card error (like a card reading as “full” when it’s empty), the SX420 also includes a Low-Level Format function. You can enable it with a checkbox on the format screen. This is a much more thorough process that methodically wipes the physical storage sectors of the card. I don’t recommend using it under normal circumstances because of the extra time it takes, but it is a great troubleshooting tool if your card starts acting up.
Notes & References:
- Depending on your computer and memory card reader setup, you might get some speed benefit when putting a faster memory card into your card reader and downloading images to your computer, but you should still format the card in the camera itself when you put it back. [↩︎]
