The Integral Ultima Pro might be cheap, but it’s still capable of respectable speeds. We logged its sequential read speeds at 96.1MB/sec and its sequential write speeds at 87.4MB/sec, although it came in slightly slower on our random read/write tests. Often, fast sequential speeds come at the expense of random read/write speeds, but the A2-class 1066x is an exception; it’s not as speedy as the Integral Ultima Pro Professional High-Speed card below, but it’s faster than the SanDisk Extreme Pro and Samsung Evo Plus on this count, making it a fine all-round performer. If you’re looking for a card that can run apps or cover video on your mid-range or high-end smartphone, you won’t get much better than this. The latest UHS-III standard is faster still, with speeds of up to 624MB/sec in both directions simultaneously, while the SD Express standard takes this up to a staggering 985MB/sec. However, neither standard seems to have taken off yet, either in terms of cards or the readers and devices to support them. Should I always buy the fastest card I can afford? What’s more, this card comes into its own on random read/write speed tests. Here, we saw the fastest performance we’ve seen from a microSD card, reaching speeds of over 12MB/sec. Other cards from Lexar, Kingston and Samsung are catching up, but this is still the speed king for app and game performance. Given that it’s only slightly more expensive than the basic Ultima Pro, that makes it one of the top options for smartphone or Switch use.

SDXC Memory Cards from 64GB, 256GB, 512GB, 1TB and 2TB | MyMemory SDXC Memory Cards from 64GB, 256GB, 512GB, 1TB and 2TB | MyMemory

The Transcend did superbly in its speed tests, excelling the claimed write speed (180MB/s) with a whopping 224MB/s, but falling slightly short on the read speed with 224MB/s. Overall, that makes this card an impressive buy at a reasonable cost. This card is ideal for high resolution, rapid-fire stills photography and 8K video, with 4K and HD video being recorded comfortably, too. On the face of it, the SanDisk Extreme Pro seems overpriced. This U3, V30, UHS-I card is significantly more expensive than the Samsung and Integral competition at most capacities, and when tested on our SanDisk ImageMate Pro card reader it wasn’t any faster, at least on sequential read and write speeds, which were 96MB/sec and 85.4MB/sec respectively.

Running out of space for your apps, games, videos or photos? Find the speed and capacity you need with our pick of the best microSD cards

As a result, those hunting for the perfect balance of price and performance don’t need to look any further, and spending just a little more will get you your card bundled with Samsung’s excellent 160MB/sec USB card reader. What more could you want?

SanDisk Ultra 64GB SDXC Memory Card, Up to 120 MB/s, Class 10

These standards cover the speed of the interface between the microSD card and your device (or memory card reader), as this can also limit the maximum speed of data transfers between the two. UHS-I has a maximum speed of 104MB/sec, and you’ll usually see a Roman numeral “I” beneath the U1 logo. UHS-II takes that up to 156MB/sec (with data transferring in both directions) or 312MB/sec (with data transferring in only one direction). Actual transfer speeds under our testing churned out a write speed of 33MB/s and read speed of 82MB/s; not too bad, but the write speed is close to the minimum V30 classification on the label, so that's worth bearing that in mind if write speeds are important to your work. Despite being rated faster than the Lexar 1000x, the Lexar Professional 1066x actually uses the slower UHS-I interface. This turns out not to be a big deal, though, as we still measured sequential read speeds of up to 157MB/sec and write speeds of 80MB/sec on our 64GB sample, with the faster 128GB to 512GB versions capable of over 120MB/sec. In other words, it’s a steal for smartphone and tablet users or anyone wanting more storage for their Switch, and still a good option for your average DSLR or compact camera. Unless you find the Ultima Pro Premium High Speed even cheaper, buy away.While the higher capacity cards increase in price exponentially, the 633x appears in sizes as small as 16GB, making it suitable for a wide range of photographers and videographers alike who require all kinds of capacities for casual or professional use. We found its write speed to be a little slow compared to other UHS-I cards in this class range, but it’s good value for money and the V30/U3 class listing means it’s still suitable for up to 4K UHD video recording. On top of this, most cards now have a “V” (for video) rating, going from V6 all the way to V90, indicating write speeds of 6MB/sec to 90MB/sec. You need a V30 card to shoot 4K video at speeds of 60 to 120 frames per second, while V60 is the base level for shooting 8K video at 60fps. V90 is theoretically capable of handling 8K video at up to 120fps. However, given that only a handful of professional-grade cameras can offer that, and that they tend to use the larger CFexpress 2.0 cards for storage, this isn’t what you might call a must-have. There are three main types of SD card: SD, SDHC (high capacity) or SDXC (extended capacity). SD cards typically offer 128MB to 2GB in storage capacity, too small for today’s modern cameras with higher resolutions. SDHC bumps this up from 4GB to 32GB, useful for most photographers and videographers. SDXC cards, meanwhile, range from 64GB to 2TB and are aimed at professional-level users who require more memory. With the right card reader, the Professional High-Speed version of the Ultima Pro can be a serious speed demon. With Integral’s own high-speed card reader, we were disappointed with its 99MB/sec and 88MB/sec sequential read/write speeds, but in a third-party high-speed reader, we saw read performance leap to 173MB/sec, with sequential write speeds of 139MB/sec. That write speed is the fastest we’ve seen from a UHS-I card. The best microSD cards to buy in 2023 1. Integral Ultima Pro Premium High Speed: Best-value microSD card at higher capacities

card 2023: Boost your capacity with our top picks Best microSD card 2023: Boost your capacity with our top picks

Our SanDisk Extreme SD UHS-I V3 tests saw write speeds live up to its claims, matching them almost exactly at 71.6MB/s. But as with most other cards on this list, the read speeds leave a bit to be desired, coming in at almost half the claimed speed, 71.6MB/s. All can be forgiven, though, bearing in mind the extremely low cost of these cards, especially while still offering such high capacity to users at up to 256GB sizes. Our stand-out best SD card is the Transcend SDXC UHS-II U3. With a Class 10, V90, U3 and UHS-II rating, we thought it would be fast enough to capture almost anything modern devices could throw at it, but we weren’t expecting the speed results we got. Card classifications like V30 or U3 are just categorizations of these speeds. There are three main classes: Speed Class (denoted with a number in a circle), UHS Speed Class (a number in an open beaker-like icon), and a Video Speed Class (V followed by a number). The numbers indicate the minimum writing speed when put under data transfer. Speed class is categorized into Class 2 (a minimum write speed of 2MB/s), Class 4 (4MB/s), Class 6 (6MB/s), and 10 (10MB/s). Choosing the best one for your camera depends on your camera's resolution, buffer size and burst shooting speeds. An additional clue is the UHS Speed Class rating, which is U1 or U3. U1 means it can write a minimum of 10MB/s (like Class 10), while U3 pushes the write speed up to a minimum of 30MB/s. More interested in shooting video? The Video Speed Classes are V6, V10, V30, V60, and V90, with V6 suitable for standard definition video recording and V90 capable of 8K video capture. 4K UHD video recording will require a minimum of V10 ideally, and HD video can utilize V6 or below at a push. How we test SD cards One final thing we need to make clear is that speeds will depend on your microSD card reader. The reader built into your average laptop might not be capable of reading from or writing to the fastest cards at their full speed, and we’ve found huge variations in external readers, even those bundled with high-performance cards. If you’re investing in one of the faster microSD cards, grab the matching adaptor from the same manufacturer, or from a credible manufacturer like Lexar, SanDisk, Kingston or Integral. That goes double for UHS-II cards. What if I’m buying for an action camera or dashcam?SD cards are flash memory, which means they have no moving parts and instead rely on electronic chips to store data. While they don’t require power to store data, they can be damaged via water, fire and physical pressure. Some companies offer bespoke 'tough' versions that can withstand these elements, even remaining safe in extreme temperatures, so it's worth looking for those if you're going on an adventure.