Canon R6 III Recommended Memory Cards for the R6 Mark III

Tim Mayo · Dec 13, 2025

I've just finished testing 50 memory cards in the R6 III, 23 CFexpress Type B and 27 UHS-II SD cards.

The R6 III isn't writing to the CFexpress slot much faster than around 505 MB/s. So because the vast majority of CFexpress Type B cards can sustain this speed and more, they mostly perform the same in-camera. There were only three cards that dropped below these speeds, which increased the buffer clearing times.

There is definitely no in-camera benefit to using the newer CFexpress 4.0 cards over the 2.0 cards, but you will benefit from up to 50% faster transfer speeds when using a 4.0 reader.

There is more of a variation in performance when it comes to UHS-II SD cards. If you need to shoot to both cards at the same time, then you will always be restricted by the speed of the SD card, so it's best to go with a fast one!

It would be great to hear what cards people are choosing to use in your own R6 III. Also if you have any issues with any cards, please do let us know.

Full details can be found in the blog post here:

Tested in Camera: The Best Canon R6 III Memory Cards - RF Shooters

In this guide we put over 50 memory cards to the test in the 32.5-megapixel full-frame Canon EOS R6 III, measuring real-world in-camera performance versus the card label speeds. But first, for those who are unaware, the Canon R6 III features dual memory card slots. Slot 1 is compatible with...

rfshooters.com

THXGEEK · Dec 13, 2025

Hey Tim (and everyone else) - any idea if a future firmware update will take advantage of the enhanced performance the 4.0 cards offer? And on the R5II as well?

Tim Mayo · Dec 14, 2025

THXGEEK said:
Hey Tim (and everyone else) - any idea if a future firmware update will take advantage of the enhanced performance the 4.0 cards offer? And on the R5II as well?

Not unless the cameras have PCIe Gen 4 hardware built-in already but have been restricted to run at PCIe Gen 3 speeds, then a firmware update could enable the faster speeds. But I expect we will never see a camera that maxes out the write speeds of either a 2.0 or 4.0 card due to the heat it would generate.

BlueBomberTurbo · Dec 25, 2025

I just bought one of those Type B 2230 SSD enclosures. Dropped a 1TB Sabrent Rocket in and it works fine for 7K RAW, in all frame rates and standard/light. $180 for 1TB Type B is a steal.

Bryan wilburn · Dec 28, 2025

Take a look at the max rate the camera can take on a sustained burst. Then select a card with a Write speed that will support that rate, and then some.

An R5 Mk II can shoot at 30 FPS, with CRAW at 24 BM each. That's an intake rate of 720 MB/Sec. At full RAW of 42 MB it jumps to 1260 MB/Sec..

So my cards have a Write rate of 1700 MB/Sec. And I don't get into a buffering catchup problem.

Bryan

Tim Mayo · Dec 28, 2025

Bryan wilburn said:
Take a look at the max rate the camera can take on a sustained burst. Then select a card with a Write speed that will support that rate, and then some.

An R5 Mk II can shoot at 30 FPS, with CRAW at 24 BM each. That's an intake rate of 720 MB/Sec. At full RAW of 42 MB it jumps to 1260 MB/Sec..

So my cards have a Write rate of 1700 MB/Sec. And I don't get into a buffering catchup problem.

Bryan

I've not had chance to test the R5II yet but I don't believe it's writing to the CFe cards at 1260 MB/s when shooting RAW, if it was then you would never fill the buffer but according to the manual you'll fill it after 230 shots with a CFe card.

I've seen some other discussions with figures ranging from 600-700 MB/s. So a card with a minimum sustained write speed of 1700 MB/s would be overkill, but future cameras might be able to write faster.

Most cards quote the max write speed on the labels and not the sustained write speeds which throws a lot of people.

The Prograde Gold 2.0 puts 1700 MB/s on the label but doesn't say if that's read or write, it's actually the max read speed, the sustained write is only 250 MB/s but you'd have to dig into the specs to find it. But for most people just shooting short bursts even 250 MB/s would be sufficient.

Bryan wilburn · Dec 29, 2025

To each his own, but form me, Overkill (within reason) is a good thing.

The reason is to get a card that will write at faster than the camera can capture data and feed it through the data bus. Most references I've seen indicate the R5 Mk II has a 2000 MB/S bus.

So a CFexpress Type B 4.0 is excessive overkill and given the speeds of close to 4000 MB/s a waste of money, at least for the R5 Mk II. Unfortunately, the Canon Specs don't list the Bus speed, and you have to dig for it.

By any chance do you have any hard data on the transfer speed of the R6 III data bus?

One of my earlier cards was easily overwhelmed by the system as it was on the slow side. Since then I buy the fastest cards available.

Tim Mayo · Dec 29, 2025

Bryan wilburn said:
To each his own, but form me, Overkill (within reason) is a good thing.

The reason is to get a card that will write at faster than the camera can capture data and feed it through the data bus. Most references I've seen indicate the R5 Mk II has a 2000 MB/S bus.

So a CFexpress Type B 4.0 is excessive overkill and given the speeds of close to 4000 MB/s a waste of money, at least for the R5 Mk II. Unfortunately, the Canon Specs don't list the Bus speed, and you have to dig for it.

By any chance do you have any hard data on the transfer speed of the R6 III data bus?

One of my earlier cards was easily overwhelmed by the system as it was on the slow side. Since then I buy the fastest cards available.

More speed doesn't hurt apart from the wallet

A new camera might come along that can take advantage of it and you can of course enjoy faster transfer speeds over to your computer, even a 4.0 card is beneficial when reading from the cards.

The R5 II just like all the other current Canon R Series with a CFexpress slot supports a theoretical maximum speed of 2000 MB/s with a CFexpress Type B 2.0 card using the PCIe 3.0 x2 interface. However, they never get close to this speed due processing overheads, and Canon probably also restricts it due to the heat those faster speeds would generate. If they were writing that fast you'd never hit the buffer no matter what file type you were shooting in, but they all hit it sooner or later with the faster frame rates.

With the R6 III I ran all my tests shooting RAW (33.9 MB) + JPEG L (10.8 MB). At 40 fps I hit the buffer after 155 shots. So that's a total of around 6928 MB. It took just under 4 seconds to hit the buffer and clears it in around 10 seconds, so because it's writing to the card when you are shooting it writes all 6928 MB in a little under 14 seconds in total, which roughly works out at 505 MB/s. In reality it's probably writing a little slower whilst you are shooting due to the additional demands on the processor and bandwidth, then once you stop shooting and it's only focussed on clearing the buffer it probably speeds up a bit, so 505 MB/s is your average speed. For some Sony cameras they are writing around 80 MB/s faster once you stop shooting, so not a big difference. I might try to work out the different speeds at some point but what most people want to know is how many shots you can take before hitting the buffer and how long it takes to clear.

Canon R6 III Recommended Memory Cards for the R6 Mark III

Welcome to our Canon RF Shooters Forum

Be apart of something great, join today!

Tim Mayo

Administrator

Tested in Camera: The Best Canon R6 III Memory Cards - RF Shooters

THXGEEK

Well Known Member

Tim Mayo

Administrator

BlueBomberTurbo

Newcomer

Bryan wilburn

Active Member

Tim Mayo

Administrator

Bryan wilburn

Active Member

Tim Mayo

Administrator

Similar threads

Latest reviews

New in the marketplace