What does “SDHX”, “Rated A2”, “100MB/s”, “Class 10”, and “V30” even mean?! Choosing the right MicroSD to extend the storage capacity of your smartphone can be complicated especially if you don’t know what all the industry jargon means. There’s a lot of variables to consider in addition to the storage capacity (32GB or 512GB) and price point. Most of the listings on Ebay, Amazon, and even Bestbuy simply just list things out like “SDHX”, “Rated A2”, “100MB/s”, “Class 10”, and “V30” as if you’re suppose to know what they mean. We decided to make a quick tutorial to give you, the educated consumer, a crash course in what these terminologies all mean, so that you can make a better decision on which microSD is right for you.
SDHC vs SDXC
SDHC is short for Secure Digital High Capacity. Meanwhile SDXC is short for Secure Digital Extended Capacity. There’s no real discernible differences between them except that SDHC usually caps off at about 32GB. Meanwhile SDXC can go up to 1TB. SDXC tends to be a bit more expensive the higher the capacity. In terms of image/video quality, they are identicle. A
Read/Write Speed
The Read and Write speed designates the relative performance of the card. Generally, if it has a fast Read speed, your media will load faster and it will be quicker for you to accessing them. If your Write speed is fast, then recording or transfering files to the card will be seamless. A good performing microSD card will have an average Read speed of about 95 – 100MB/s and a Write speed between 80 – 90MB/s. The higher these numbers, the better.
Class and UHS ratings
Each microSD will have a “Class” rating attached to it. The Class rating just means the minimum transfer speed it allows for. UHS is short for Ultra High Speed, and cards classified as UHS will usually have higher minimum transfer speeds. V Classes are relatively new and more widely available today. You’ll mostly need to worry about V classes if you plan to record a lot of HD/1080/4K videos and want fast transfer speeds. Below is a quick chart to give you an idea of the different classes and what their minimum transfer speeds are.
Also, don’t be confused by the minimum speed. This isn’t the same as their read/write speed.
| Class |
Minimum Speed |
| 2 |
2 MB/s |
| 4 |
4 MB/s |
| 6 |
6 MB/s |
| 8 |
8 MB/s |
| 10 |
10 MB/s |
| UHS 1 |
10 MB/s |
| UHS 3 |
30 MB/s |
| V6 |
6 MB/s |
| V10 |
10 MB/s |
| V30 |
30 MB/s |
| V60 |
60 MB/s |
| V90 |
90 MB/s |
Application Performance Class
This is a feature specific for smart phones and tablets and something you should pay close attention to. For those who plan to save applications onto their microSD cards, the Application Performance Class (either A1 or A2) determines the random random read input-output access per second, IOPS for short. A1 typically has a read IOPS of 1500 and write IOPS of 500. Meanwhile A2 has a read IOPS of 4000 and write IOPS of 2000, making it A2 significantly better at running apps. You’ll notice a performance boost when using apps saved to your microSD if it has either A1 or A2.
In short, if a microSD is rated either A1 or A2, it’s going to be great for smartphones and tablets. And if it’s rated A2, it’s REALLY good.
Video Quality
Make sure to check to see if the card offers 4K or not. If it doesn’t, chances are you won’t be able to record/save in 4K. Most modern smartphones will have 4K video recording as an option, so if you’re using the microSD for a smartphone, this may be an important criteria.
Durability And Protection
MicroSD cards are built fairly enough nowadays. Most offer the standard protection such as being temperature proof, shockproof, waterproof, dust-proof, and x-ray proof. Be sure to check to see if the one you’re planning to buy has the protection you need. The level of protection can be important if you’re using the microSD in an outdoor security camera or if your device will be subjected to harsh conditions.
Price
And of course you want to make sure the microSD card you’re choosing fits within your budget. Their price can range drastically depending on the brand, capacity, and features. We’ve compiled a list of the best microSD cards here.
And there you have it, everything you need to know in order to make an educated decision on which microSD card to purchase for your newest Android smartphone. We’ve also curated a list of best microSD cards for Samsung galaxy phones here, so if you have the latest Samsung, be sure to check out this article first before committing.
