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
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, with some up to a massive 2TB.
Cards above 32GB are called 'SDXC cards' and can be used with devices that support this standard. Currently 2TB is the limit, though the biggest microSD cards you can currently buy are 512GB.
If you're wondering about the new SD Express standard that was announced in June 2018, that's currently only for full-size SD cards. It does hint of what's to come for microSD, though. In essence it turns them into tiny portable SSDs, with capacities up to 128TB and speeds of up to 985MB/s. Fortunately, you don't need to worry about this as there are no devices which support SD Express, let alone the microSD version.
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.
It can be confusing to choose a card as there are so many standards and logos. Some markings refer to speed, others to capacity. Here's how to figure them out.
The newest standards are 'V' and 'A', and you'll see a number after each which represents a minimum standard of performance.
Best microSD for video recording
Basically, if you're buying a microSD card to record video, you'll want to look for one with a V10 logo or better. The number after the V is the guaranteed write speed in megabytes per second (MB/s), although it may be higher than this.
To record 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.
Best microSD for phones and tablets
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 or A2 logo on a card. A2 is very new, but A1 cards should be fast enough for running apps and games.
So which card should I buy?
Stick to the well-known brands which will offer a warranty on their cards. Reputable brands include: Samsung, SanDisk, Lexar, Kingston, Integral 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 good reason!
How we test microSD cards
We use CrystalDiskMark 6.0 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 Plus
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 Plus is now the entry-level range, with the Pro Plus and Pro Endurance being more expensive.
We tested the 128GB card, but it's also available in 32GB/64GB/256GB capacities.
The packaging boasts of "Write Speed up to 90 MB/s" and we saw a sequential write speed 84.3 MB/s so it's not far off the claim. Read speeds weren't quite up to the 100 MB/s claim but at 88.3 MB/s, you won't be disappointed given the price of the Evo Plus.
For phone and tablet use, you're more interested in 4KB performance, and here the Evo shines: it scored 10.5 MB/s when reading and 4.7 MB/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.
You can buy microSD cards that work out cheaper per gigabyte, but the Samsung Evo Plus offers the sweet spot where you get great performance at a great price.
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 and 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.
SanDisk Ultra microSD
If you don't fancy going for SanDisk's top tier cards, its Ultra range also offers solid performance for much lower prices per GB - along with the option of stepping up to a capacious 256GB.
In our CrystalDiskMark testing it managed sequential read speeds of 89MB/s - just a little shy of the 95MB/s SanDisk claims - though write speeds were a more modest 27MB/s. That's fine for recording full HD video, but falls a little short of what you'd require for quality 4K video recording.
If you want to use the card in a phone or tablet (or a Nintendo Switch, for that matter) you'll probably be more concerned with the 4KB speeds, and this is where the SanDisk Ultra is more impressive, managing to read at 9.4MB/s and write at 2.4MB/s. That's not the very best out there, but it's better than most and very solid performance for a card this price.
Many modern phones have a microSD slot that allows you to add up to 2TB of storage. However, that’s academic since the largest cards until now have been limited to 256GB in capacity.
Integral is the first company to break through that barrier and its latest card offers double the storage at 512GB. That’s still a mere quarter of the 2TB limit, but it’s still a considerable amount of storage when even the largest-capacity phones top out at 128GB.
Integral’s card isn’t just for phone or tablet users, though. It’s ideal if you have a Nintendo Switch and want to install a whole library of games.
Similarly, if you want a huge card for recording HD video on an action camera or drone, it’ll handle that task with ease as well. It’s particularly good for a home security camera that records continuously to microSD.
What it can’t do is handle 4K recording: it’s rated as V10, the lowest of the new video recording standards. In our tests, we found it managed a sustained write speed of 19.3MB/s. That’s plenty for Full HD 1920x1080 resolution though.
Read speeds are much quicker at 83.6MB/s – a whisker short of the 85MB/s claim.
For use in phones and tablets, you should be more concerned about a card’s 4KB file performance. Here the Integral puts on an impressive show with 7.3MB/s for reading and 1.7MB/s for writing.
When you calculate the cost per GB, it’s not as cheap as you might hope for (though the smaller capacity cards are much better value), but if you need this much storage, it’s currently your only option.
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 it 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 4KB 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.