V30 vs V60 SD card, and which your camera needs

V30 promises the card will never write slower than 30 MB/s during video. V60 promises 60 MB/s. Divide your camera's video bit rate in Mbps by 8 and buy the class just above that number.

The SD Association defines these classes as a guaranteed minimum sustained write speed, which matters because video writes data without pausing. The big number printed on a card's front is usually its top read speed, and it tells you little about recording.

The sum

• 100 Mbps video is 12.5 MB/s, so V30 is plenty.
• 200 Mbps is 25 MB/s, and V30 still covers it.
• 600 Mbps is 75 MB/s, which needs V90.

Real cameras need some headroom, so follow the maker's table where one exists. Sony asks for V30 at 200 Mbps on the A7 IV but V60 for the same bit rate in slow motion.

What we recommend by camera

These come from our checked catalogue, matched to what each camera's video needs.

If your camera is in the V30 row, a V60 card gives you no better video.

Do not confuse V with UHS

UHS-I and UHS-II describe the card's connection to the camera. V30 and V60 describe guaranteed writing speed. They are separate labels. A UHS-II card works in a UHS-I slot at UHS-I speed, so a fast card in a slow slot wastes money.

CFexpress cards use a different system called VPG, so V classes do not apply to them.

Before you buy

Say your camera model and the video format you use. A good camera shop will read the mark on the card with you and tell you if you are over-buying. Check that the V number really is printed on the card, and buy where you can come back if it misbehaves.