Video Speed Class Explained (V30, V60, V90)

Video Speed Class is the industry standard for measuring whether a memory card can sustain the write speeds that video recording demands. Understanding V-class ratings prevents the most common memory card mistake: buying a fast card that still drops frames.

Why Sustained Speed Matters

Maximum write speed (the headline number on the box, like "280 MB/s") describes the fastest burst a card can achieve under ideal conditions. Sustained write speed is what the card can maintain continuously over minutes of recording. Video recording demands sustained writes because the camera never stops writing — every frame must land on the card within a fixed time window or the buffer overflows.

Video Speed Class defines a guaranteed minimum sustained write speed. A V60 card guarantees at least 60 MB/s continuously, regardless of what the max speed on the box says.

The Classes

| Class | Minimum sustained write | Typical use case | |---|---|---| | V30 | 30 MB/s | Standard 4K at moderate bitrates (up to ~100 Mbps) | | V60 | 60 MB/s | High-bitrate 4K, 4K 60fps on many cameras | | V90 | 90 MB/s | 8K, 4K 120fps, RAW video recording |

How to Read a Camera's Requirement

Camera manufacturers publish the minimum card requirement per recording mode. This is usually stated as:

• A V-class rating: "V60 or faster required for 4K 60fps"
• A UHS Speed Class: "UHS Speed Class 3 (U3) required for 4K"
• Or a raw MB/s figure for CFexpress: "VPG200 (200 MB/s minimum)" for certain modes

U3 = 30 MB/s minimum, which is equivalent to V30. V-class is more informative for video use because it goes higher and is specifically designed for video workloads.

What Happens With an Underpowered Card

The camera detects that the card is not writing fast enough and stops recording. Some cameras show an error ("card write speed too slow"); others just stop mid-clip without warning. In either case, footage is lost.

Which Class Do You Need?

V30 is sufficient for:

• 4K 30fps at standard bitrates (under 100 Mbps) on most mirrorless cameras
• 1080p at any frame rate
• SD-slot recording on dual-slot bodies where the SD slot has a lower bitrate ceiling

V60 is required for:

• 4K 60fps on Sony A7-series, Canon EOS R6 Mark II, Fujifilm X-T5, Nikon Z30, and many others
• All-intra 4K recording on Lumix cameras
• SD-slot on Sony FX3 and FX30 for their mid-bitrate 4K modes

V90 is required for:

• 8K recording (Sony Alpha 1, Canon EOS R5 Mark II)
• 4K 120fps RAW on Sony bodies
• ProRes RAW / Canon Cinema RAW Light on flagship bodies

VPG (Video Performance Guarantee)

CFexpress cards may carry a VPG rating (VPG200, VPG400). This is a CFexpress-specific sustained speed guarantee similar to V-class, measured in MB/s. VPG200 = 200 MB/s minimum sustained. Not all CFexpress cards carry a VPG rating — absence of a VPG label does not mean the card fails; it means the rating was not tested or published by the manufacturer.

When CompatKit evaluates a pair involving a CFexpress card, we check whether the card's published minimum sustained write speed (from the manufacturer's spec page) exceeds the camera's stated requirement for each recording mode.

Checking a Specific Pair

Every compatibility pair on this site shows the specific write-speed comparison between the card and camera. Browse by camera to see all verified pairs, or check a specific pair directly.