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Speed labels on SD cards look confusing. Here is what each one means.

Last updated: November 1, 2026.

Class, U and V ratings

Class 10, U1 and U3 describe minimum write speed; V30, V60 and V90 describe video sustained speed.

UHS-I vs UHS-II

UHS-II is faster but needs a compatible device. See UHS-II SD cards.

A1 and A2

App ratings matter for phones and handhelds. See microSD cards.

Frequently Asked Questions

Do I need V90?

Only for high-bitrate video.

Is Class 10 enough?

For basic use.

Do speeds matter for photos?

Less than video.

Bottom Line

Match the rating to your device, not to the biggest number.

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