Best Micro SD Card of 2021
Do you have a need for speed? For a fast writing SD card, look no further than the SanDisk 64GB Extreme Pro MicroSDXC. This card easily handled every task we threw at it in our testing, from 4K video shoots to rapid-fire RAW images, and achieved an impressive maximum write speed of 86 mb/s. For those that like gadgets, this card notably meets the often strict minimum speed requirements of the vast majority of drones. With the SanDisk Extreme Pro, you're likely never going to have to worry about the speed of your card.
All of this performance doesn't come for free, as the SanDisk Extreme Pro is noticeably more expensive than the average card on the market. However, that price difference is relatively small in comparison to the performance benefits. We think the small extra cost will be well worth it for most people considering the reliability and versatility afforded by the extra speed.
Unless you're using a fancy camera drone or dabbling in advanced photography techniques, chances are you can get away with a less than agile card. If that's the case, we think the Samsung 32GB EVO Select MicroSDHC offers a great value. Though its maximum measured write speed of 35 mb/s is only mediocre, it is more than fast enough for most tasks. In fact, in our tests, it was easily able to record 4K video and even shoot bursts of RAW images for a short period, so you shouldn't have any issues using it in a phone or security camera. All of this comes at a relatively good value, particularly if you're shopping for some of the higher-capacity options.
Across the board, the EVO Select posted below-average speeds in our tests. In a functional sense, this mostly showed up in our RAW image burst tests, where the EVO Select could only shoot for a few seconds before getting bogged down. Its specs are also such that the software of speed-sensitive things like drones may not be compatible. Despite these drawbacks, the EVO Select still provides a good bang for the buck.
If you want a fast card but don't want to pay top dollar, the SanDisk 64GB Extreme MicroSD is a good option. Its measured write speed of 67 mb/s allowed it to easily record 4K video in our tests, and it withstood a full 5 seconds in our tortuous RAW image burst shooting test. It is also likely to be fast enough for use in most consumer camera drones, though we recommend checking the specs first.
The SanDisk Extreme is cheaper than the faster cards on the market, but not by much. If you're concerned about speed, you'll likely want to spend a few extra dollars to get the best. However, if you want to save a few bucks and get the cheapest card that meets the minimum speed specs of the device you're using, the SanDisk Extreme might be a perfect compromise.
MicroSD cards are a cheap and effective way to instantly upgrade the internal storage of your phone or tablet (unfortunately, most Apple devices don't offer such an option). If that's your main goal, the SanDisk 128GB MicroSDXC for Nintendo Switch is a near-perfect solution. Not only does it provide a lot of storage at a relatively reasonable price, but it is also fast enough that you probably won't notice you're accessing your files from an 'external' storage device. In our tests, the maximum write speed of 70 mb/s allowed us to quickly offload photos and videos from our phones to free up space, and the solid read speeds let us view those same photos and videos without any lag or delays.
The lack of a standard SD card converter is the main drawback of this card. We think the need to purchase a converter separately in order to use a full-sized SD card reader is a bit of a pain. However, if you're sure you'll only be using the card in your phone or tablet, the lack of an extra piece of plastic could be a pleasant surprise. For phone or tablet storage expansion, you can't do much better than the SanDisk 128GB MicroSDXC for Nintendo Switch.
The Samsung 128GB PRO Endurance MicroSDHC offers a lot of storage space for a relatively low price. It's designed for continuous recording devices, such as security or dashboard cameras, and that extra storage is ideal for those applications. The 41 mb/s speed is likely to be plenty fast enough for its intended use, and we even found it suitable for 4K recording in our tests. Samsung advertises the card as water, magnet, temperature, and X-ray proof.
While this card is fast enough for most applications, it may lag a bit if used for advanced RAW photography, and may be too slow for some of the advanced consumer drones that require faster memory cards. If you're looking for a lot of storage on the cheap, the Samsung PRO Endurance will likely meet your needs.
The Samsung 128GB EVO Plus MicroSDXC is a high-capacity card that displayed an elite write speed of 86 mb/s in our tests. This impressive speed means it will likely be fast enough for almost any use. Its higher capacity configurations are also a bit less expensive than those of other similarly fast models on the market. Like many cards, it sports a manufacturer claim that it's impervious to water, temperature, magnetic fields, and X-rays.
Though this card offers more gigabytes per dollar than many of the faster cards available, it is still significantly more expensive than average. Still, the Samsung EVO Plus can provide a combination of fast speeds and lots of storage for less than many of the competitors.
Basic tasks, like recording HD video from a security camera or taking standard photos, generally don't require much speed, which can often allow you to get away with a less expensive card. The SanDisk 16GB Ultra MicroSDHC can work well in such situations. Despite its measured write speed of 12 mb/s being rather glacial compared to many other cards, it still managed to record 4K video in our tests without a glitch. Thus, it will likely work well for most basic, non-speed-intensive tasks.
The SanDisk Ultra doesn't leave much room for growth, and will likely bog down if you use it in more demanding situations/devices. If your SD card needs are fairly basic, the SanDisk Ultra is still a relatively inexpensive option.
Why You Should Trust Us
We designed our microSD card testing processes with the help of our in-house photographers, Laura Casner and Jason Peters. These two professionals have multiple decades of photography and videography experience between them and have used just about every form of solid-state memory cards currently available. Senior Editor Max Mutter has been testing and writing about consumer technology products for nearly five years. In that time, he's used more than 100 devices that require the use of microSD cards, making him intimately familiar with their function, speed classes, and idiosyncrasies.
Our microSD card testing relies on a mix of objective measurements and performance in real-world situations. We measured each card's speed while writing and reading the same large video files and the same folders full of photos, providing us with directly comparable speed measurements. We then corroborated these results with functional tests, using each card to record 4K video, to shoot bursts of memory-intensive RAW images, and to expand the storage of our phones and other devices.
Analysis and Test Results
Write speed, or the speed at which a card can record data, is the most differentiating factor of microSD cards. These speeds can also differ quite a bit depending on what types of files are being written. We focused our testing and ratings on two performance areas: large file write speed, or how quickly a card can write video files, and small file write speed, or how quickly a card can write groups of smaller files like photos. We also tested and considered read speeds, or how quickly cards can transfer existing data. Read speeds, however, are less differentiating and thus only important for more niche situations.
Large File Write Speed
The ability to quickly write large files can allow a card to record high-quality video without dropping any frames or resulting in any pixelation. To measure large file write speed, we transferred the same 5GB 1080p video file onto each card and timed the process. This allowed us to calculate a speed in megabytes per second (mb/s). Large files are the easiest for solid-state storage devices like microSD cards to write; therefore, we dubbed this measurement the maximum measured write speed. We then used each card to record 5 minutes of 4K video, all with the same camera, to see how well each card worked in real-world scenarios. This latter test was conducted in a pass/fail manner (any dropped frames or pixelation resulted in a fail). All of the cards that made our final cut passed this test.
The SanDisk 64GB Extreme Pro MicroSDXC and Samsung 128GB EVO Plus MicroSDXC were the fastest of the UHS-I cards that we tested, reaching a maximum speed of 86 mb/s. The SanDisk 128GB MicroSDXC for Nintendo Switch and the SanDisk 64GB Extreme microSD came close to these speeds, hitting respective clips of 70 and 67 mb/s in our tests.
Beyond this point, we saw a significant drop-off in terms of large file write speed. Even the slowest cards, however, were able to function well for basic uses like recording 1080p HD video. If you're conducting more advanced tasks or using devices like top-tier camera drones that require faster cards, you'll want to go with one of the top-performing cards mentioned above.
Small File Write Speed
Small file write speed largely corresponds to a card's ability to quickly process and save many images in rapid succession. To test this, we transferred the same 5GB folder filled with almost 2000 photos onto each card and timed each transfer. We then put each card into the same camera and shot a burst of RAW images at full speed until the card started to lag and bog down. While performing this test, we held a microphone near the camera and recorded the sound of the shutter onto a basic music production program. The resulting waveform provided a visual representation of how many images each card could write in rapid succession before reaching its limit and slowing down.
Three cards shared the top speed in this metric, with the SanDisk 64GB Extreme Pro MicroSDXC, the Samsung 128GB EVO Plus MicroSDXC, and the SanDisk 128GB MicroSDXC for Nintendo Switch all logging a top speed of 36 mb/s (small file speeds are generally slower than large file speeds). All these cards also lasted more than 5 seconds in our RAW image burst test.
Beyond these top performers, most cards fell into the 20 mb/s range. Even the slowest card, however, was able to last 3 seconds in our RAW image burst test, indicating that any card should be more than capable of handling basic imaging tasks.
Read speeds come into play when you are extracting data from a card, such as when uploading all the videos and photos you took on your vacation to a computer. We tested read speeds by transferring the same video and photo files we used in our write speed tests from each card onto the same computer, using the same card reader.
The read speed results were quite consistent across the board, with pretty much every card hitting speeds of about 94 mb/s when reading large files, and about 78 mb/s when reading groups of small files.
MicroSD cards may seem a dime a dozen, but if you look under their fragile plastic frames, there are actually noticeable differences. We hope our test results help you wade through the sea of arcane stats and marketing claims that often accompany these cards, and lead you to the perfect model for your intended use.
— Max Mutter