Just any old card won’t do though, especially if you’re trying to record HD or 4K video - you need the right one for the job. Here we explain how to choose a card and recommend those that you should buy.
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MicroSD card buying guide
Frustratingly, there are at least four different 'standards' for microSD cards which makes it extremely confusing when trying to compare them. Here's the kind of thing you can expect to see:
Some markings refer to speed, others to capacity. Here's how to figure them out.
Before you buy a card, check the maximum size that your device can accept. Dash cams are particularly limited - most will take up to 32GB, the limit of the SDHC standard - but most phones will support up to 256GB.
Cards with bigger capacities can be used with SDXC devices, which go right up to 2TB, though the biggest microSD cards you can currently buy are 512GB.
Do I need a specific card for a camera or a phone?
Short answer: yes. Longer answer: some cards are so good, they're capable of recording 4K video in your GoPro but will also give great performance in your phone.
Basically, if you're buying a microSD card for any device that records video, you'll want one with a high 'sequential' transfer speed. There's a new rating system starting to appear on cards for video to help identify them.
You'll see something like V90 or V60. The number refers to the write speed in megabytes per second. The higher the better, but for 4K video, you should aim for at least V30. The SD Association has recommendations for speeds you need for recording at different video resolutions.
If there's no 'V' number, check the packaging or specifications to find out the write speed. Watch out because the biggest number is usually the read speed, not write.
On the other hand, you might be buying a card to expand your phone or tablet's storage. Here you need good performance for reading and writing small files.
That's why the other new rating system is 'App performance', denoted by an A, followed by a number.
It works in a similar way to the video class, and you'll see an A1 logo on a card which meets the minimum requirements which are:
- Random Read Input-Output access Per Second (IOPS) of 1500
- Write IOPS of 500
- Sustained Sequential performance of 10MB/s.
The logo looks like this:
What is UFS? The new microSD card explained
Confusing things even further, Samsung has unveiled the 'successor' to microSD, known as UFS or Universal Flash Storage. These cards come in 32-, 64-, 128- and 256GB capacity and are much faster (five times faster, in fact) than microSD, with sequential read speeds up to 530 megabytes per second.
Samsung says UFS can read a 5GB full-HD movie in around 10 seconds, whereas it would take a UHS-1 microSD card around 50 seconds.
Write speeds are also lightning-quick, up to 170MB/s. That's almost double the speed of the fastest microSD cards available today.
No gadgets today support UFS cards, but the technology will be coming in the near future. You should note, though, that microSD and UFS cards are not interchangeable - you must buy the type of card listed in your device's specifications.
So which card should I buy?
Stick to the well-known brands which will offer a warranty on their cards. Reputable brands include: Toshiba, Samsung, SanDisk, Lexar, Kingston and Verbatim, among others.
There are plenty of fakes and counterfeit microSD cards, so make sure you buy from a trusted seller. If you see a card on eBay that’s a lot cheaper than you expect it to be, there’s probably a reason!
How we test microSD cards
We use CrystalDiskMark to test the read and write speeds of each card. This tests both the sequential speeds (reading and writing large blocks of data) and small-file performance, using 4KB reads and writes.
Tests are carried out on our Intel Core i7-based test rig over USB 3.0. We use the full-size SD adaptors which come with cards and a Lexar Professional USB 3.0 Dual-Slot Reader. If a card comes with its own USB 3.0 adaptor, as with Lexar's own card, we use that instead.
Samsung Evo microSD
Samsung is one of the biggest brands, so you're likely to sway towards buying a Samsung-branded microSD card, especially if you have a Samsung phone. The Evo+ is the faster variety: the plain Evo here is a mid-range UHS-I card that's aimed at phone and tablet use.
The sample we were sent by Ebuyer didn't come with an adaptor in the pack: you're supposed to slot it into your mobile and never need to use it in a full-size SD slot. However MB-MP64DA model does come with one, and there's another version with a USB adaptor.
The Evo has a 10-year warranty, which is one of the longest around.
The packaging boast of "up to 48MB/s Transfer Speed with UHS-I" and we saw a sequential read speed 45.8MB/s (47MB/s dead with zero queue depth) so it's right on the money. Write speeds aren't half bad either: 26.5MB/s in the multi-threaded sequential test and this increased significantly to over 39MB/s with no queue depth.
For phone and tablet use, you're more interested in 4KB performance, and here the Evo shines: it scored 9MB/s when reading and 3MB/s when writing.
This makes it one of the best choices overall, especially if you're sticking it in a phone that's capable of recording 4K video. However, the Evo Plus is only a couple of quid more expensive, is faster and comes with an adaptor. For reference, the Evo (the MB-MP64D version) works out at roughly 20p per GB. It's cheap as chips!
SanDisk Extreme Plus microSD
The Extreme Plus is SanDisk's flagship range of microSD cards, and it certainly doesn't disappoint. It claims up to 95MB/s read speeds and 90MB/s write. It's rated both A1 and V30.
We were impressed when we saw it return over 87MB/s and 85MB/s for reading and writing in CrystalDiskMark. In fact, it went even faster in short queue depth test, with 92MB/s for reads and almost 88MB/s for writes.
That makes it a superb choice for recording video in 4K drones and action cameras, or burst photography in a DSLR. It's also a fine performer for phones and tablets thanks to strong 4KB performance of 9.3MB/s when reading at 4MB/s when writing these tiny files.
It's a fantastic microSD card that's only held back by its high price of over 70p per GB. Unless you need these high speeds, you'll find better value elsewhere.
Kingston microSD Action Camera
Available in 16, 32 and 64GB capacities, the Kingston microSDAC card is designed for action cameras (that's what the AC stands for). It's a UHS class 3 card, which means is must write at a minimum of 30MB/s.
You can buy it with or without the full-size SD adaptor and you'll actually save a few quid by going without.
It wasn't too surprising, given the aim of this card, to see very poor random 4K performance, so don't buy this thinking you'll swap it into a phone or tablet at some point.
No, this card is purely for sticking in your GoPro or drone and recording video. With sequential write speeds of 70MB/s, this card is the third fastest for writing that we've tested, and way faster than the 45MB/s it claims on the packaging. It's also very quick at reading - just under 90MB/s (which is what Kingston claims).
All versions work out at about 50p per GB, which makes it the best-value microSD card for recording 4K or high frame-rate slo-mo video.
Verbatim Pro+ microSD
The Pro+ is a UHS-I Class 3 microSDXC card which claims to read at up to 90MB/s and write up to 80MB/s. It comes with an adaptor which turns it into a full-size SD card.
Our tests showed that our 64GB card it didn't live up to those figures, maxing out at a whisker under 67MB/s for sequential reads, and only 44MB/s for writing. Not the slowest by any means, but some of its rivals (the SanDisk Extreme Plus) got much closer to similar claimed speeds.
It's perfectly adequate for Full HD recording, and also has enough pace for 4K too - but other cards are significantly faster.
For tablet or phone use, it's a mixed bag, managing almost 12MB/s when reading 4KB files - a decent speed, but less than 1MB/s when writing them.
You can find it for less than £30 if you hunt around, but at roughly 50p per GB, it's certainly not the cheapest option.
Lexar Professional 633x microSD
Unlike most microSD cards, Lexar bundles this one with a USB 3.0 dongle rather than a full-size SD adaptor. Interestingly, it's intended to be used in "sports cameras" as well as phones and tablets, and boasts of 95MB/s on the packaging (that's what 633x means = it's 633 * 150KB/s). It's an UHS-I Class 1 card, and it's the one DJI ships with it's Phantom 4 drone.
That 95MB/s is - of course - a read speed, and Lexar doesn't mention a write speed, only stating that it is "lower". We were a bit disappointed then, to find that after managing a great 92MB/s read speed when using the included dongle, it managed only 32.4MB/s when writing sequentially. A *lot* lower, then.
4KB performance wasn't outstanding either: it managed 7.7MB/s when reading and 1.3MB/s writing small files. Without the long queue depth in CrystalDiskMark it went slower still: 7.2MB/s and 0.8MB/s respectively.
It's not all bad news, though. The card is certainly fast enough to record 4K video and it's cheaper than you might expect at about 30p per GB.
Transcend Ultimate microSD
Transcend's Ultimate range offers good performance and a lifetime warranty, and also uses MLC technology.
It's not cheap: £40 for at 64GB card makes it one of the most expensive here at over 60p per GB. The 32GB version works out cheaper per GB, but only marginally.
The good news is that it almost matched the SanDisk Extreme Plus for sequential read and write speeds: 85.8MB/s and 82.8MB/s respectively.
It couldn't keep up in the 4KB tests, though, averaging 8MB/s when reading and 1.5MB/s for writing. That's quicker than average, but the cheap-as-chips Samsung Evo outperforms it for phone and tablet use.
The Transcend Ultimate is really only a sensible choice if you need the fastest write speeds for high-bitrate 4K recording, where it almost matches the SanDisk card, but at a cheaper price. It's much better value in the US, where it costs less than $40.
PNY Turbo Performance microSD
PNY’s Turbo Performance microSD card is designed for 4K action cams (or drones) with a claimed 90MB/s speed, although as we found out during our testing, this refers to read speeds rather than write speeds.
Using CrystalDiskMark, we saw fairly decent results with 90.4MB/s read speeds and 62.2MB/s write speeds. The latter is more than enough for recording 4K in consumer cameras, but it's not the fastest we've seen.
But what about for use in smartphones and tablets? With a focus on action cameras, it’s not surprising that its random 4KB performance wasn’t the greatest with read speeds of 7.1MB/s and write speeds of only 0.6MB/s. So don't buy it with a view to sharing it between your action camera and an Android phone.
In terms of price, it works out at 63p per GB for the 32GB version, so it’s noticeably more than the Kingston microSD Action Camera card which also performs slightly better.