SD Cards

There are many different classes etc. for SD cards and here I collect the data over it on one page

First, there was the speed class, which went from Class 2 to Class 10. Then there was the UHS Speed Class, where the cards fall into either U1 or U3. More recently, there’s a newer system, the Video Speed Class, that uses categories like V30, V60, and V90.

And now the SD Association has come out with a new rating system specifically to categorize suitability for SD and microSD cards in application-heavy uses. It’s known as the Application Performance Class Specification, and it’s written in the form of A1 or A2.

So, we start with these first

Application Performance Class

Application Performance ClassPictographMinimum Random ReadMinimum Random WriteMinimum Sustained Sequential Write
Class 1 (A1)1500 IOPS500 IOPS10 MB/s
Class 2 (A2)4000 IOPS2000 IOPS10 MB/s
Application Performance Class

Speed Class

Speed ClassMinimum Sequential Write Speed
22 MB/s
44 MB/s
66 MB/s
88 MB/s
1010 MB/s
Speed Class

UHS Speed Class

UHS Speed ClassMinimum Sequential Write Speed
110 MB/s
330 MB/s
UHS Speed Class

Video Speed Class

Video Speed ClassMinimum Sequential Write Speed
V66MB/s
V1010MB/s
V3030MB/s
V6060MB/s
V9090MB/s
Video Speed Class

x Speed Factor

Some manufacturers, like Lexar, also set an X Speed on their cards. To better have an overview of them here also a small table about it.

x Speed FactorMinimum Sequential Write Speed
100x15 MB/s
120x18 MB/s
133x20 MB/s
150x23 MB/s
200x30 MB/s
400x60 MB/s
600x90 MB/s
633x95 MB/s
1000x150 MB/s
1400x210 MB/s
1800x270 MB/s
2000x300 MB/s
2500x375 MB/s
3000x450 MB/s
4000x600 MB/s
5000x750 MB/s
X Speed

SD Card Bus Type

But pay attention that there is a UHS bus type too which is not to be compared with UHS speed…

SD Card Bus TypeMaximum Speed
UHS-I104 MB/s
UHS-II312 MB/s
UHS-III624 MB/s
SD Express985 MB/s
SD Card Bus Type

There is a certain amount of backwards compatibility between UHS-I and UHS-II. You can use either card type in any camera or SD card reader that accepts an SD card. The critical thing to understand is that both the device and the SD card must be UHS-II compatible if you want to unlock the additional speed benefits of the UHS-II interface.

Types of SD Card

SD Card TypeCapacity
SD128 MB → 2 GB
SDHC4 GB → 32 GB
SDXC64 GB → 2 TB
SDUCup to 128 TB

What do you need?

At the end we just need to mention what speed you need for what 🙂

I just mention the starting speed – all above is of course better

8k Video → 30 MB/s → U3 → V30

4k Video → 6 MB/s → Speed Class 6

1080p Video → 4 MB/s → Speed Class 4

Standard Video → 2MB/s → Speed Class 2

So, as you see if you only have cards with Speed Class x you can’t record 8k videos as example but should be enough, starting at class 6, for 4k videos. Of course, I recommend using U3 / V30 cards for 4k recording to be sure.