MicroSD Card Buying Guide: Everything You Need To Know

Buying a microSD card for your tablet can feel pretty daunting, especially if all you want is more storage. Why do some microSD cards cost multiple times the cheapest one?

Well, you do pay for what you get. Here’s a rule of thumb: “The more you pay, the likelier your microSD card will perform more consistently and faster.“

Furthermore, if you skimp on the quality, you could have a low-quality microSD card which means data integrity degrades much quicker over time. The chips will be down sooner rather than later.

What’s The Best SD Card For You?

Although it might be a bit shocking to think that you can be paying twice or thrice for the same amount of storage, your card will be much better for long-term use if you buy the best card you can afford.

As you can see, SanDisk has three tiers of 256GB microSDs, with each step up costing more and more.

SanDisk 256GB model	Price
Ultra	$15
Extreme	$20
Extreme Pro	$30

Between the Ultra and Extreme series, there’s a bump in speed and consistency, just based on the icons on the card. I’ll explain how to read the symbols below.

“Buy cheap, buy again” can ring true with SD cards. Here’s a possible scenario down the road. You own a tablet and for now, it only records 1080p videos. Your entry-level SD card works with no problems.

But down the road, you might get a device that records 4K or more. I bought a 360-degree camera and it won’t take low-end cards. It’ll just stop recording. On my phone, it’ll switch to recording 4K video onto internal storage, even if I have set it up to record onto my SD card.

Sometimes, manufacturers can create SD cards that seem completely alike, such as the Extreme and Extreme Pro series above. They have the same speed labels and really only differ in design.

In order to tell the difference, you’d have to do your own research. However, some reasons why a manufacturer would create a microSD card under a different name include the maximum size of the card or how many times the card can be overwritten reliably.

Cards that are meant for repeated writes (for use in dashcams or surveillance cameras) can sometimes be labeled as “Endurance” cards, and you’ll notice vast differences in longevity with different brands, according to this research. For example, the SanDisk High Endurance lasted 10,000 hours of HD recording, whereas its Max Endurance cousin lasted six times longer.

While nothing can totally futureproof you from technological obsolesce, buying the best microSD card will help you avoid that for years to come.

Fake microSD Cards?

There have been allegations of fake SD cards, so it does pay to buy your SD card from a reputable store such as Best Buy or Staples.

Fake SD cards are difficult to spot because the packaging and print on the card can look indistinguishable from the real thing.

I actually received a 1TB Samsung card from my friend and that was a few years ago. It died after a few uses and down went all my data with the card. I should have smelled a rat — 1TB was unheard of a few years ago and the price my friend told me he bought it for was suspicious.

It really does pay to buy the best card from a reputable seller.

microSD card Symbols

If you are buying a new microSD card for your tablet, camera, or smartphone, here are all the symbols that you will need to be aware of, ordered by importance.

Rule of thumb: the larger the number, the better the performance.

microSD App Performance Class

Currently, there are two standards for the App Performance Class for Running Smartphone Apps.

According to the SD Association, “The App Performance Classes assure minimum random and sequential performance speeds to meet both run and store execution time requirements under given conditions.”

They have created this table to highlight the differences between the two ratings.

Basically, if you are going to run programs and apps on your device, you will do better if you bought a card with at least an A1 rating, if not an A2.

Video Speed Rating on microSD Cards

Suppose you are going to record videos or take many photos in quick succession. In that case, Video Speed Rating is particularly critical because you will need a minimum amount of speed to avoid disruptions and unwanted pauses during photo- or video-taking.

SD cards with specific symbols guarantee a minimum amount of sequential write speed. Here’s a table from the SD Association,

You should focus on the Video Speed Class, as it determines how large you can record. Most microSD cards at the start of 2024 are V30 cards which can do 4K videos, but if you already have an 8K camera with a frame rate over 60 fps, you’ll need a V60 or V90 microSD card.

The SD Association has another image that helps you visualize what kind of V-rating you need.

The rest of the speed symbols are less relevant today, so we won’t elaborate on those. Here’s the V-class with the resolution of the video you can record.

• V6 (AKA Class 6): SD to HD video recording
• V10 (AKA U1 or Class 10): Up to Full HD
• V30 (AKA U3): Up to 4K
• V60: 4K UHD to 8K
• V90: 8K UHD videos

UHS Bus Interface Speed Standards

You might notice a tiny Roman numeral on your SD card.

It’s most likely a single “I”, but soon you’ll start seeing “II” or “III”.

In the pursuit of higher speeds, your future SD cards might have a second row of contacts. Most cards now will have one row of nine pins, but you might soon buy one with 17 pins over two rows.

microSD cards with one row of contacts can only transfer up to 104MB/s (UHS-I), whereas microSD cards with two rows of contacts can transfer up to 312MB/s (UHS-II) or 624MB/sec (UHS-III).

Remember that you’ll need both your card and your device to be mutually compatible in order to get the benefits. You can still plug in a faster SD card into a slower device, but you won’t gain the additional speed benefits.

SDUC, SDXC, SDHC, SD Capacity-Based Classification

Cards today are sold in gigabytes (e.g. 64GB, 256GB, etc.) or terabytes (1TB, 2TB, etc.).

The size of your card will determine whether it gets an SD, SDHC, SDXC, or SDUC capacity rating.

Every device has a limit as to how big of a card it’ll take. My Microsoft Surface Go tablet can only take up to 2TB, which is the limit of an SDXC memory card. Therefore, it can also take any class of card that is smaller than 2TB, including cards marked SDHC and SD. It won’t take an SD card with the SDUC class, which is given to any SD card beyond 2 TB up to 128 TB. Here’s an infographic from the SD Association that illustrates this.

If you buy a reasonably-sized card for a relatively new device, you probably won’t face any issues. It’s when you stick a very new card into a very old device that you might run into problems.

Read: Is 64GB Enough For An iPad? Here’s How Much Storage You Need

What is SD Express?

If you see the words “Express” or “EX” on your SD card, then welcome to the forefront of SD card tech. They’re the same size as regular SD/microSD cards and are the fastest SD cards out there.

Look at those speeds as defined by the SD Express specification, though. They surpass even the fastest V90 rating.

SD Express cards promise up to 3940 MB/s transfer speeds that can serve as removable solid-state drives.

The high speed allows users to record super-slow motion videos, and RAW photos in continuous burst mode. In addition, because of its high speed, it can compete with internal hard drives in terms of speed when loading software.

But wait! Even though an SD Express card is the same size as a non-SD Express card, you won’t get the speed benefits if you just connected it to any regular SD card port. It’ll still work, but it’ll be bottlenecked by the limits of the UHS-I interface.

Conclusion

If you are going to buy a microSD card, you should think about where you’re going to use it in.

If you are going to record video with it, look at the V-speed. Buy a card that’s as fast as possible based on the video your camera can record. If you record 4K, then get a card that’s at least rated V30.

If you are going to load apps on it, then you need to focus on the Application Performance Class. Buy something that’s labeled “A2” to ensure the best consistency.

If you notice that your card has a UHS-II or III rating, then you need to know whether or not your device supports this new class of SD card with two rows of contacts. If not, you will not get the extra benefits in speed.

Finally, always check what’s the maximum supported capacity of the SD card you want to buy. This is especially critical if you’re buying an SD card today for a device from many years ago.