V30 vs V60 vs V90: which SD card does your camera actually need?

V30, V60 and V90 look like a simple good-better-best ladder. For video, they are more useful than that: each number is a minimum sustained write class in megabytes per second. The right card is the one whose class matches the camera's recording mode and whose interface matches the card slot.

The expensive mistake goes both ways. A card that is too slow can stop a take. A V90 card in a camera and mode that can use only V30 may do exactly the same job as the cheaper card.

What the V number guarantees

SD Association defines those Video Speed Classes and distinguishes them from the large maximum read or transfer speed printed elsewhere on a package [1][2]. “Up to 300 MB/s” is not the same promise as V90. One is a best-case peak under stated conditions; the other is a class floor under the Video Speed Class method.

The association also places V30 in the UHS bus family and V60/V90 in UHS-II or UHS-III [1]. This matters physically: a UHS-II card has a second row of contacts. Put it in a UHS-I-only camera and it falls back to the interface both support. The card remains usable, but the host cannot invent the missing faster bus.

Convert the camera bitrate

Camera menus and manuals usually state Mbps (megabits per second). Card speed is usually MB/s (megabytes per second). Divide by eight:

Card data rate in MB/s = video bitrate in Mbps ÷ 8

Examples:

Do not round a 35 MB/s stream down to V30. Its payload already exceeds the 30 MB/s class floor. And do not treat the table as permission to ignore the manual: a camera may write proxy video, audio, metadata or two files, and slow-motion modes can change the requirement.

A real camera table shows why the manual wins

Sony's official help guide provides a clean example [3]:

• XAVC HS 4K and XAVC S 4K modes up to 280 Mbps specify SDXC V60 or higher.
• XAVC S-I 4K at 600 Mbps specifies SDXC V90 or higher.
• At 200 Mbps, the same guide notes that U3/V30 can be used in the applicable case.
• Some high-frame-rate settings require a higher card or CFexpress even when the ordinary mode uses SD.

These examples are not universal Sony rules, much less rules for every brand. They show the correct method: find the exact format, bitrate, frame rate and secondary-recording options in the exact model manual.

Video speed and photo bursts are different questions

V-class is designed around sustained recording. A high V-class card may also write stills quickly, but burst performance depends on more:

• the camera's buffer size;
• RAW/JPEG file size and whether both are saved;
• the camera's UHS-I or UHS-II implementation;
• the card's actual write curve above its class floor;
• how quickly the card recovers after a long burst.

If burst clearing matters, test the camera-card pair or use a trustworthy sustained-write result for the exact capacity. Different capacities in one card family can use different internal parallelism. The V logo alone does not promise a particular number of RAW frames before slowdown.

A practical buying rule

1. Open the manual's supported memory card table.
2. Select the exact codec, bitrate, frame rate, slow-motion and proxy/dual-recording combination.
3. Buy the stated V class or higher, in a card technology the slot supports.
4. Check maximum supported capacity and filesystem.
5. Buy from a traceable seller and test the full capacity.
6. Format in-camera and record a clip longer than your normal take at the hardest setting.

If the camera requires V60, V90 may still be worthwhile for faster offload or another V90 body — but only if the reader, cable and computer complete that faster path. Otherwise the extra rating is unused insurance.

Bottom line

V30, V60 and V90 mean 30, 60 and 90 MB/s minimum class write rates. Convert Mbps to MB/s, but let the camera's mode table make the final decision. V60 is the natural step when the payload exceeds 30 MB/s; V90 covers modes such as 600 Mbps recording that exceed V60's floor. Match the slot too, because a fast card cannot upgrade the camera's bus.