The best microSD cards

• From smartphones to cameras and gaming devices, microSD cards are the go-to for external storage.
• But not all microSD cards are the same, and picking one can be complicated. The letters and numbers found on microSD cards can be incredibly confusing, and you need to consider the speed or capacity (or both) depending on how your device will use the card.
• Overall, the Samsung EVO Plus microSD card does the best job in speed and capacity options for the best price, although you should also consider the SanDisk Extreme microSD UHS-3 Card and the SanDisk Ultra microSD card.

Sometimes, the storage that's built into a device just doesn't cut it (and sometimes there is no built-in storage option) - that's where microSD cards come in to expand your device's storage.

Many Android smartphones, including the Samsung Galaxy Note 10 and LG V50 ThinQ 5G, support microSD cards - a minuscule version of the larger SD format - as do all GoPro Hero action cameras and small cameras like it; consumer drones, like those from DJI; and mobile gaming devices, like the Nintendo Switch.

Before we get into our top picks, let's go over those aforementioned confusing numbers and letters so you know what they mean and why they're important for your device.

Card type and capacity

When it comes to the card type, the two main kinds you'll want to consider are SD HC (Secure Digital High Capacity) and SDXC (Secure Digital eXtended Capacity). The only real difference between the two is how much storage they offer. SDHC cards contain 4GB to 32GB, while SDXC starts with at least 64GB of capacity and extends up to 2TB (and beyond, in the near future).

Although most newer devices accept the SDXC standard, some older gadgets, like the GoPro Hero4 and Nintendo 3DS, will only support lower-capacity SDHC microSD cards of 32GB or less. Consult your product's user manual to see what it recommends before purchasing any card.

In general, you should get as much capacity as your budget allows. And depending on what you plan to do with the card, you will also need to consider the speed class, which we'll explain below. The card speed and capacity will determine pricing.

Speed class

Speed class is where things get complicated. The chart from the SD Association below breaks it down visually, but we also will explain below.

MicroSD cards are measured in six speed classes: 2, 4, 6, 10, U1, and U3 (this also applies to standard SD cards, if you were wondering). The class number refers to the write speeds (how fast it can record onto the card) in megabytes per second (MB/s), so Class 2 = 2MB/s, Class 4 = 4MB/s, Class 6 = 6MB/s, and Class 10 = 10MB/s. U1 supports at least a 10MB/s write speed, and U3 cards offer at least a 30MB/s write speed, but there's something to keep in mind with U1/U3.

Most new cards support Class 10 or higher; from our observation, you're less likely to see new cards being sold that are Class 6 or lower. But you may also see a card with both Class 10 and U1 or U3 designations. This means the card is also compatible with the Ultra High Speed (UHS) bus (in computing, a bus is the system that transfers data between components). MicroSDXC cards will always carry a Class 10 and either U1 or U3, as well as higher-end microSDHC cards.

For example, a microSDHC or microSDXC card with both Class 10 and U1 classifications will support faster transfers (U1) when used in devices that support UHS, but will throttle down to the slower transfer speed (Class 10) in most other devices. (Note: If an older device supports Class 6 or lower, you can still use the faster card we mentioned in our example, but you won't achieve the higher write speeds.)

A high-end card will also list either UHS-I or UHS-II. This is in reference to the theoretical top bus speed and is not to be confused with the write speeds mentioned above. UHS-I Cards have a maximum speed of 104 MB/s, while UHS-II cards have a maximum speed of 312 MB/s - compare them to non-UHS cards, which have a theoretical speed of 25 MB/s. Cards that support UHS-II offer even better performance, naturally.

Lastly, as the above image shows, there's a classification called Video Speed Class. With the increase in devices that can capture very high-resolution video, the SD Association - the governing board that created all these designations - created the Video Speed Class for cards that support these higher video resolutions, like 4K, 8K, virtual reality, 360-degree, and 3D. This classification is denoted with a V and followed by a number, which represents the speed in MB/s. For example, a V30 card will support a minimum write speed of 30 MB/s. Video Speed Class is rated as V6, V10, V30, V60, and V90. Cards labeled with a Video Speed Class are designed to support those aforementioned resolutions, according to the manufacturer.

App Performance Class for smartphones and tablets

The App Performance Class denotes which MicroSD cards are best for smartphones and tablets. An A1 rating means that the card can open apps and process apps quickly, because it can handle a random read input-output access per second (IOPS) of 1,500 and write IOPS of 500. A1 cards are new, and anyone who wants to use Google's "Adoptable Storage" feature, which formats your card as internal storage in an Android device, should look for the new rating.

The right microSD card for your device

Depending on what you're using your microSD card for, you'll want the right amount of capacity.

For smartphone users: Because the photo and video capabilities of modern smartphones have dramatically increased in quality, we recommend avoiding SDHC cards entirely, and starting at the 64GB capacities found in SDXC cards. The price of microSD cards, even at high capacities, has plummeted in recent years, so price should not be nearly the inhibitor it once was. With that said, although modern phones can support cards up to 1TB, unless you're taking a lot of photos and videos, you are unlikely to ever need that much capacity. If you like to shoot 4K video on your phone, then you should buy an SDXC microSD card that has a U3 speed class rating, with 128GB or 256GB capacity. Many phones, including the Samsung Galaxy Note 10 and LG V50 ThinQ, support SDXC microSD cards with up to at least 1TB of storage (the LG V50 actually supports up to a whopping 2 TB).

For the Nintendo Switch and 3DS: The Nintendo Switch accepts SDXC microSD cards with up to 2TB of capacity. Since games take up a lot of storage, we recommend you get the highest-capacity card for your Switch that you can afford. The older Nintendo 3DS only supports SDHC cards (32GB or less), so don't waste money on high-capacity SDXC cards.

For GoPro and similar small cameras: If you need a microSD card for your GoPro, consult the company's list of recommended cards. The site says that GoPros require a minimum of Class 10, but U1 or U3 are better speed classifications. The Hero8 supports SDXC microSD cards with up to 128GB of capacity, as does the DJI Osmo Action. We have been testing the Hero8 with a SanDisk 32GB SDHC U1 card and have not had any issues

Avoid poor quality cards made by less scrupulous manufacturers by sticking with tested and verified brands and clicking on our links.

Here are the best microSD cards for your phone, GoPro, or Nintendo Switch:

• Best microSD card overall: Samsung EVO Plus microSD card
• Best microSD card for action cams or drones: SanDisk Extreme microSD U3 Card
• Best microSD card for the Nintendo Switch: SanDisk Ultra microSD card

Updated on 11/12/2019 by Jaron Schneider: Updated recommendations and copy. Added new version of the SanDisk Ultra microSD cards and the new SanDisk Extreme microSD card. We are currently testing new options for our next update.