MicroSD card speeds simplified: V30 A2

If you want to buy a decent general purpose MicroSD card in 2022, buy something that says “V30” and “A2”. I’m happy with the Sandisk Extreme. It works pretty well as the primary disk in a Raspberry Pi and will also work for 4K video, maybe even 8K.

In detail.. There’s a confusing array of different class definitions for SD cards. Ignore “Speed Class” (2, 4, 6, 10) or UHS (1 or 3); those are obsolete. Also ignore SDXC, SDHC, and SDUC; those refer to storage capacity and you can just read the size.

The primary throughput rating on a card now is V, for Video Speed, and modern choices are V30, V60, or V90. V30 is 30Mbps and is fine for 4K video. There’s a nice chart here of speeds. Note a V30+ card will also probably be labeled “Speed Class 10” and “UHS 3”. Faster is better but you pay for it, so unless you know you need it save your money.

The only random access rating on a card is Application Performance Class and comes in two ratings: A1 or A2. There’s no real price increase for A2 so get that. This isn’t so important for recording video but means absolutely everything for use as a general hard drive, say in a phone or a Raspberry Pi. A2 isn’t so great; it’s 4000 read IOPS. Compare 600,000 IOPS for a fancy SSD. But at least it’s got a rating. Old fashioned spinning disks are more like 50-200 IOPS, so even that A2 is a big improvement over what we used to use.

The Sandisk Extreme 128GB I like is $20 for 128GB, V30, A2. Some prices for various speeds of 128GB cards from NewEgg

  • V10 A2 $13 – $17
  • V30 A1 $11 – $20
  • V30 A2 $11 – $20
  • V60 A2 $27
  • V90 A2 $100

V30 A2 is the sweet spot for performance; no point getting anything slower for general use. You pay a significant premium for V60 or V90. By all means pay that if you need it, but you probably don’t. 128GB seems to be the sweet spot for storage; 64GB cards cost almost the same.