V30 vs V60 vs V90: SD Card Speed Classes Explained

V30, V60 and V90 are guaranteed minimum sustained write speeds of 30, 60 and 90 megabytes per second, and for most beginner cameras a V30 card is all you need. A Sony ZV-E10 records 4K at up to 100 megabits per second and a Canon EOS R50 at about 120, which works out to 12.5 and 15 megabytes per second — half of what a V30 card guarantees, or less. V60 earns its place on cameras such as the Sony a6700 and Canon EOS R10, whose makers ask for it in their highest-bitrate 4K modes. V90 is for All-Intra and slow-motion formats that most beginners never switch on.

This guide goes deeper than the short buyer's guide in our best SD cards for 4K videoranking: what every mark on the label means according to the SD Association, the body that writes the SD standard; why the biggest number on the card is the least useful one; and the arithmetic to check any camera against any card. We have not bench-tested cards. The figures come from the SD Association's pages, a card maker's data sheet and the camera makers' own manuals and spec tables, all linked in Sources.

One card, several rating systems

A current SD card can carry four or five speed marks at once, because the standard has added new systems over the years without retiring the old ones. What they share is the idea: each is a guaranteed minimum speed for sustained, sequential writing under conditions the standard defines — a floor, not a peak. The SD Association states the reason plainly: video recording needs a constant minimum write speed to avoid dropped frames. Here is how the systems line up.

Three things follow from that table. First, the marks overlap. U3 and V30 guarantee the same 30MB/s floor, and U1 and V10 the same 10MB/s. That matters because Canon's spec tables ask for "UHS Speed Class 3" while the packaging leads with V30: they are the same requirement. Second, the SD Association defines V60 and V90 on the UHS-II and UHS-III buses, so any V60 or V90 card is a UHS-II card or faster — which matters for which cameras can use it, covered below. Third, the suggested uses are broad strokes. The SD Association pitches V90 at 8K, but what decides your card is your camera's bitrate, not the resolution printed on the box.

The biggest number on the label is a read speed

Take the 256GB SanDisk Extreme PRO, the card we rank first below. SanDisk's data sheet gives it three different speeds: up to 200MB/s read, up to 140MB/s write, and V30. Each one answers a different question.

• 200MB/s is a read speed— how fast files come off the card when you copy them to a computer. SanDisk's own footnote says reaching it relies on proprietary technology that goes beyond the UHS-I bus's 104MB/s and requires compatible devices, and it recommends its own reader to hit the figure. It says nothing about recording.
• 140MB/s is a peak write speedfrom SanDisk's internal testing. The same data sheet quotes up to 90MB/s for the 64GB and 128GB versions of the same card, so even this number changes with capacity.
• V30 is the guaranteed floor: at least 30MB/s of sustained writing, under the conditions the SD standard defines. It is the only one of the three that is a guarantee rather than a best case.

A video recording writes continuously for minutes at a time, so the floor is what protects your footage; a card that manages 140MB/s in a short burst guarantees nothing above 30MB/s for a long clip. Peak write speed matters for a different job — clearing a burst of still photos, covered after the picks — and read speed matters only when you offload. SanDisk's fine print makes the general point itself: performance "may be lower depending upon host device, interface, usage conditions and other factors."

The math: divide the bitrate by eight

Camera makers quote video bitrates in megabits per second (Mbps). Card makers quote speeds in megabytes per second (MB/s). There are eight bits in a byte, so divide the camera's number by eight and compare it with the card's floor. A 100Mbps video stream needs 12.5MB/s of sustained writing; a 600Mbps stream needs 75MB/s. Here is what that looks like for four popular beginner and step-up cameras, next to what each maker actually asks for.

Bitrates and card requirements are from Sony's Help Guide card tables for the ZV-E10 and a6700 and Canon's published specifications for the R50 and R10. Canon lists its bitrates as approximate. The "needs about" column is simply the bitrate divided by eight.

What the table tells you, camera by camera

Sony ZV-E10 and Canon EOS R50:every mode stays well under V30's floor. The ZV-E10 tops out at 100Mbps, or 12.5MB/s. The R50's most demanding mode, Full HD high frame rate with HDR PQ, is about 180Mbps, or 22.5MB/s. Both makers ask for no more than U3. A V30 card covers either camera with room to spare, and a V60 or V90 card buys nothing while recording. Our Canon R50 reviewcovers the rest of that camera's video features.

Canon EOS R10:the interesting one. Its cropped 4K at 60 frames per second writes about 28.8MB/s in standard 8-bit mode — inside V30's 30MB/s floor, but by a hair, and Canon only asks for U3. Switch on HDR PQ and the same mode climbs to about 42.5MB/s, and Canon's table asks for V60. If you shoot 4K 60p on an R10 at all, buy V60 and stop thinking about it.

Sony a6700:Sony organizes its card table by format and lists each format's top bitrate, so its 4K formats as a whole call for V60 or higher, and its slow-motion and All-Intra formats for V90. The Help Guide adds that slow-motion recording raises the bitrate above normal. Even if your everyday setting would fit a V30 on paper, follow the table: V60 for 4K, and V90 only if you use slow and quick motion or XAVC S-I. Our Sony a6700 review explains those video modes.

Leave headroom, and trust the maker's table over the math

The math tells you whether a class is plausible; the camera maker's table tells you what it has actually approved. Bitrates are quoted as approximate or as a maximum, and a card's floor is measured under the standard's test conditions, not inside your camera. So use two rules. When your converted number sits within a few megabytes per second of a class floor, as the R10's 4K 60p does, buy the next class up. And when the maker's table asks for more than the math suggests, as Sony's does for the a6700, follow the table. The bitrate you choose in the menu sets the card you need, so it is worth understanding those settings — our best camera settings for video guide walks through them.

UHS-I vs UHS-II: the bus is a ceiling, not a floor

The speed class is the guaranteed floor. The bus is the connection between card and camera, and it sets the ceiling. The SD Association rates UHS-I at up to 104MB/s and UHS-II at up to 312MB/s. UHS-II cards get there with a second row of pins, which use a different signaling method; full-size UHS-II cards have 17 pins against 9 on UHS-I cards. The first row of pins is kept for backward compatibility, so a UHS-II card works in a UHS-I camera — at UHS-I speeds.

That is why the bus matters for which class you buy. Sony describes the a6700's slot as UHS-II compatible, and Canon's R10 specifications list UHS-II support; the R50 supports UHS-I only. Since V60 and V90 are defined on the UHS-II bus, a UHS-I camera like the R50 cannot take advantage of either rating. It will record happily to a V60 card, but you pay for speed it never uses in camera.

So the answer sorts itself. A V30 UHS-I card is the right card for the ZV-E10, the R50 and most beginner bodies. A V60 UHS-II card is the right card for the a6700's 4K and the R10's 4K 60p. A V90 card is for the a6700's slow-motion and All-Intra formats, or any camera whose manual asks for it. Here are the cards that meet each bar, in that order.