The 10 Best Micro SD Cards

Editor's Notes

November 25, 2020:

First of all, ensure that it is a microSD card that you want, and not a larger miniSD card or an even larger standard SD card.

Current Trends in the MicroSD Market
While it’s becoming less common to find support for microSD cards on newer phones, many new Android smartphones like some LG and Samsung Galaxy phones still come with microSD card slots, though the current trend is leaning more towards applications in cameras, dashcams and camcorders, drones, PC’s and laptops. Cards that fall into the SDXC capacity category definitely dominate the market today, with newer devices being built to handle them and the exFAT file format, and nowadays, a 64-GB SDXC card barely costs 3-5 bucks more than its 32-GB counterpart. Even cards with higher capacities of 128-GB and 256-GB do feel more like the standard today, and the latter typically costs around 50 bucks. I suppose that might change going forward, with the advent of SDUC cards. If you do have an older device that can only take up to SDHC cards, then I’ve left in the Samsung Pro Endurance from the last update. All the newer options I’ve added however offer SDXC as these seem to reflect the current market more accurately.

Updates to This List
The previous editor had done a good job of including some models that are still fairly relevant today, and there wasn’t a pressing need for me to replace too many items on the list. SanDisk still makes some of the best cards in the market, with both the SanDisk Extreme Plus, as well as the SanDisk Extreme Pro - which I've just added - being represented here, though, I have whittled down the options from this brand. Previously, there was the Extreme A1 and Extreme A2. The A2 was virtually the same model as the Extreme Plus, and fairly similar to the A1, with the only difference being that the A2 has a higher Class 2 Application Performance Rating, which means that it has higher random read and write speeds than a card with an A1 rating. The Pro offered some variety and joins both the Lexar 1000x and Lexar Professional 1800x as a model with a UHS-2 bus system. Note that there are versions of the Pro with a UHS-1 bus system.

The ‘A’ rating is a measure of the card’s ability to read and write random data, and as the previous editor mentioned, this is important for mobile apps and other applications where you’re accessing data in a non-sequential way. While most options in this list also have an A1 Application Performance Rating, the Lexar 667x which I’ve added as a replacement for the Lexar 633x, as well as the Arcanite A2 have an A2 rating, along with the SanDisk Extreme Plus.

In contrast to the ‘A’-rating, the ‘V’ rating – or Video Speed Class - is one of the many classification systems that highlights the sequential speed of a card, and models with a classification of V60 or higher are able to support 8K video at 120fps. As previously noted, the Lexar Professional 1800x is ideal for 8K video, with its V90 rating.

I was initially tempted to replace the Lexar 1000x with an option that also had V60 and UHS-II rating, but I struggled to find a more reasonable card with the same specs. There were some off-brand models with lower capacities - 128-GB vs. the Lexar’s 256-GB – but, they didn’t offer as good value for money.

How To Read an SD Card’s Specs
I thought I’d postface this editor’s note with a brief explanation for the novice of what those often-confusing symbols on microSD cards mean. I will keep this brief, and not delve into too much detail on each technical specification.

Capacity Class: the first thing you may see on your SD card which can be found on all types of SD is some stylized writing – that may say microSDXC, microSDHC or otherwise. This indicates the storage capacity class that the card falls into:
• SD or SDSC (Secure Digital Standard Capacity) – up to 2 GB; these are rarely seen on the market nowadays
• SDHC (Secure Digital High Capacity) – 2 to 32 GB; you can still find these in the market, but they’re becoming less and less common
• SDXC (Secure Digital Extended Capacity) – 32 GB to 2 TB; these is currently the most common class of cards on the market
• SDUC (Secure Digital Ultra Capacity) – 2 GB to 128 GB; these are currently very hard to find on the market, but should become commonplace in the years to come.

Capacity in gigabytes: in addition to the capacity class of a card, you’ll also see the specific capacity of that card. An SDXC card may have a 128-GB capacity for instance, or an SDHC card may have a 32-GB capacity.

Sequential Speed
This takes into account the transfer – read and write - speeds, and is basically a measure of how quickly the data can be recorded to a card, and is an important consideration for the quality of video recording. If you use a card that’s too slow in a 4K camera for instance, the recording may stop frequently because the card simply can’t keep up. Typically with older forms of the cards – like the standard SD card - you’ll find the maximum read speed printed on the card itself – i.e. 95MB/s. Write speeds will be a little lower.

In multiples of X: Another mode of read speeds that’s more commonly employed by certain makers, particularly Lexar, uses an archaic unit of measurement that would list a speed as a multiple of the speed of the first CD-ROM drives, which were 150KB/s.

You’ll also find some other notations on the cards that indicate their minimum write speeds:

C Rating – the ‘C’ or class rating is usually denoted by a symbol that has a number circumscribed with a ‘C’. A C6 rating for instance indicates a minimum write speed of 6MB/s while a C10 indicates a minimum write speed of C10. Most cards nowadays have a C10 rating.

UHS(Ultra-High-Speed) Class – as cards began to get faster, ratings had to get higher, and the UHS or U-class rating is basically an extension of the C rating. A U1 rating would indicate a minimum write speed of 10MB/s, while a U3 indicates a speed of 30MB/s. You can spot the UHS Class on a card as a number circumscribed by a funny-looking ‘U’. Another thing you may see is the UHS bus system employed by the card, which is denoted by a I or II. Basically, a ‘I’ indicates that a card uses one set of contacts, and a ‘II’ means that it uses two sets of contacts.

V(Video) Class – nowadays, you may also see a ‘V’ with a number next to it, denoting the video class, which is sort of another extension of write speed classifications as a result of faster and faster cards. A V30 has the equivalent write speed of 30MB/s and is ideal for Full HD video recording, a V60 – with a minimum write speed of 60MB/s – is ideal for 4K video and okay for 8K video too, and a V90 rating is ideal for 8K video.

Random Speed
I’ve already mentioned the application – or ‘A’- class rating, which is a measure of the random read and write speeds, and was introduced as a reflection of the need to measure the effectiveness of an SD card at accessing random data, in light of its growing use in mobile applications. Instead of measuring in MB/s, this type of speed is measured in IOPS (Input/Output access Per Second).

May 31, 2019:

Smartphones and tablets usually leave a little to be desired on the storage front, but as long as you're not using an Apple product, that's generally quite easy to overcome with a good micro SD card. There are two levels of performance to be aware of. Sequential throughput measures how fast the card works with large files in continuous blocks, while random read and write speeds are far more relevant to mobile devices. You'll notice SanDisk has a lot of models on our list; believe it or not, they're all slightly different, and most of them offer fantastic random read/write, making them all great choices for expanding smartphone storage. The Extreme A2 is particularly interesting because it's the first with a 1-terabyte version, though even if you are able to get your hands on one, it'll cost you quite a bit. The Extreme A2, while not offered in as large of sizes, shows the best promise for app loading in real-world benchmarks.

If you need a card for use in your top-of-the-line camera, you might want to consider a UHS-II model. This is an advanced bus that uses two rows of pins rather than one. There aren't any phones as of this writing that utilize this two-row system, but it is backward-compatible with UHS-I. If you want to guarantee the best large-file performance, get the Lexar Professional 1800x. It truly can't be beat and will definitely suffice even if you're recording 8K video. Lexar's other models are also quick, but they don't leverage the most advanced bus; they are, however, considerably more affordable. And you really can't go wrong with Samsung, because they're largely considered to be the most reliable producer of flash memory in the world, and their various high-speed options are available at decent prices and in large capacities.