SD Cards

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 Class	Pictograph	Minimum Random Read	Minimum Random Write	Minimum Sustained Sequential Write
Class 1 (A1)		1500 IOPS	500 IOPS	10 MB/s
Class 2 (A2)		4000 IOPS	2000 IOPS	10 MB/s

Speed Class

Speed Class	Minimum Sequential Write Speed
2	2 MB/s
4	4 MB/s
6	6 MB/s
8	8 MB/s
10	10 MB/s

UHS Speed Class

UHS Speed Class	Minimum Sequential Write Speed
1	10 MB/s
3	30 MB/s

Video Speed Class

Video Speed Class	Minimum Sequential Write Speed
V6	6MB/s
V10	10MB/s
V30	30MB/s
V60	60MB/s
V90	90MB/s

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 Factor	Minimum Sequential Write Speed
100x	15 MB/s
120x	18 MB/s
133x	20 MB/s
150x	23 MB/s
200x	30 MB/s
400x	60 MB/s
600x	90 MB/s
633x	95 MB/s
1000x	150 MB/s
1400x	210 MB/s
1800x	270 MB/s
2000x	300 MB/s
2500x	375 MB/s
3000x	450 MB/s
4000x	600 MB/s
5000x	750 MB/s

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 Type	Maximum Speed
UHS-I	104 MB/s
UHS-II	312 MB/s
UHS-III	624 MB/s
SD Express	985 MB/s

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 Type	Capacity
SD	128 MB → 2 GB
SDHC	4 GB → 32 GB
SDXC	64 GB → 2 TB
SDUC	up 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.