Tested in Camera: The Best Sony A6400 Memory Cards

Welcome to my Sony a6400 memory card guide with in-camera speed tests.

I’ve owned the a6400 since it was first launched and I’ve tested quite a few different memory cards in-camera to figure out which are the best SD cards to buy.

Top 6 Sony a6400 Memory Cards

Here are my top 6 recommended memory cards for the Sony a6400 along with my in-camera speed test results.

1. SanDisk Extreme Pro UHS-I (170/90)

The SanDisk Extreme Pro SD cards are rated V30 for video and have a claimed read speed of 170MB/s and a write speed of 90MB/s.

Here are my in-camera speed test results:

Image Type	Shots Before Hitting Buffer	Time to Clear Buffer (Seconds)
RAW (24.9MB)	51	24.97
Compressed RAW (17.4MB)	115	41.55
RAW + JPEG (24.9MB + 17.4MB)	47	44.28

Shooting RAW these cards have an in-camera write speed of around 40.42MB/s.

2. Sony Professional Series UHS-I (95/90)

The Sony Professional Series SD cards are rated U3 and have a claimed read speed of 95MB/s and a write speed of 90MB/s.

Here are my in-camera speed test results:

Image Type	Shots Before Hitting Buffer	Time to Clear Buffer (Seconds)
RAW (24.9MB)	51	25.40
Compressed RAW (17.4MB)	115	41.75
RAW + JPEG (24.9MB + 17.4MB)	47	44.38

Shooting RAW these cards have an in-camera write speed of around 39.91MB/s.

3. SanDisk Extreme UHS-I (150/70)

The SanDisk Extreme SD cards are rated V30 for video and have a claimed read speed of 150MB/s and a write speed of 70MB/s.

Here are my in-camera speed test results:

Image Type	Shots Before Hitting Buffer	Time to Clear Buffer (Seconds)
RAW (24.9MB)	51	25.72
Compressed RAW (17.4MB)	115	41.98
RAW + JPEG (24.9MB + 17.4MB)	47	45.09

Shooting RAW these cards have an in-camera write speed of around 39.41MB/s.

4. Sony Expert Series UHS-I (94/70)

The Sony Expert Series SD cards are rated U3 and have a claimed read speed of 94MB/s and a write speed of 70MB/s.

Here are my in-camera speed test results:

Image Type	Shots Before Hitting Buffer	Time to Clear Buffer (Seconds)
RAW (24.9MB)	51	25.82
Compressed RAW (17.4MB)	115	42.00
RAW + JPEG (24.9MB + 17.4MB)	47	45.13

Shooting RAW these cards have an in-camera write speed of around 39.29MB/s.

5. Transcend 500S UHS-I (95/60)

The Transcend 500S SD cards are rated V30 for video and have a claimed read speed of 95MB/s and a write speed of 60MB/s.

Here are my in-camera speed test results:

Image Type	Shots Before Hitting Buffer	Time to Clear Buffer (Seconds)
RAW (24.9MB)	49	32.43
Compressed RAW (17.4MB)	107	52.57
RAW + JPEG (24.9MB + 17.4MB)	45	65.79

Shooting RAW these cards have an in-camera write speed of around 31.45MB/s.

6. Lexar 64GB Professional 633x UHS-I (95/45)

The Lexar 64GB Professional 633x SD cards are rated V30 for video and have a claimed read speed of 95MB/s and a write speed of 45MB/s.

Here are my in-camera speed test results:

Image Type	Shots Before Hitting Buffer	Time to Clear Buffer (Seconds)
RAW (24.9MB)	49	41.41
Compressed RAW (17.4MB)	107	52.66
RAW + JPEG (24.9MB + 17.4MB)	45	66.18

Shooting RAW these cards have an in-camera write speed of around 25.43MB/s.

Although there are many more brands of memory card on the market, the cards listed above are the best performing cards that have also received the highest average reviews at stores like Amazon and B&H Photo.

I don’t recommend cards that are known to have reliability problems.

In-Camera Write Speed Test Explained

The speed tests that I perform to work out the fastest memory cards are fairly straight forward.

I use my Sony E 18-135 lens, manually focus on my target (1/1000th Sports Photography of Bob Martin), set the aperture to f/3.5, shutter to 1/200, ISO to 100 and Drive Mode to Hi+ for the maximum frames per second.

I press the shutter button and time how long it takes before the buffer is full (when the LCD goes blank and shooting slows). I also time how long it takes for the buffer to clear. I repeat this test until I get 3 results with the identical number of shots taken. I then average the buffer clearing time and total time of these 3 results.

This will give me the number of shots taken before filling the buffer, the average time taken to clear the buffer and the average total time from start to finish.

The faster the memory card the more shots you will be able to take before filling the buffer, this is because files are also being written to the SD card whilst shooting thus clearing the buffer for more shots.

For the a6400 I do this test shooting RAW, extra fine JPEG and JPEG + RAW.

I calculate the average in-camera write speed by taking the number of uncompressed raw shots, multiplying this by the RAW file size (24.9MB) then dividing by the total time taken to shoot and clear the buffer.

Which Memory Cards are Supported?

The Sony a6400 supports SD memory cards, SDHC memory cards (UHS-I compliant) and SDXC memory cards (UHS-I compliant). The following memory cards are supported via an adapter: Memory Stick PRO Duo, Memory Stick PRO-HG Duo, Memory Stick Micro (M2), microSD memory cards, microSDHC memory cards and microSDXC memory cards.

Memory Card Slots

The Sony a6400 has a single memory card slot. If you need a camera with dual memory card slots then you’d need to move to full-frame and I’d recommend taking a look at a camera like the Sony a7III.

JPEG and RAW File Size

Jpegs vary in size considerably depending on the quality you are shooting in (standard, fine, extra fine) and the number of colors in the image. They can be anywhere from a couple of megabytes up to around 25MB. A RAW file from the a6400 is approximately 25.6MB in file size.

Maximum Memory Card Capacity

The Sony a6400 has no documented maximum memory card size, although they do list the number of images recordable on cards up to 256GB. The largest card that I’ve personally tried using is the SanDisk Extreme Pro Memory Card 256GB. However, I really wouldn’t recommend putting all of your eggs into one basket. It’s a lot more sensible to use smaller cards like 64GB or 128GB.

What Size Memory Card Do You Need?

If you are shooting stills then I would recommend a minimum memory card size of 64 GB. If you shoot a lot of continuous bursts then 128GB will keep you shooting for longer before you need to change cards.

For shooting video the size of memory card will depend greatly on the format that you are recording in.

The following two tables should help you to decide which size memory card you will need depending on your record settings for both stills and video.

Maximum Number of Still Images Recorded by Memory Card Size

The table below shows the approximate number of images that can be recorded on a memory card formatted within the a6400 and shot with an aspect ratio of 3:2.

The values may vary depending on the shooting conditions and the type of memory card used, so please use these figures as a rough guide only.

JPEG Quality / File Format	8 GB	32 GB	64 GB	256 GB
Standard:	1300	5300	10500	40000
Fine:	810	3300	6600	26000
Extra Fine:	405	1600	3250	1300
RAW & JPEG:	215	880	1750	7000
RAW:	295	1200	2400	9600

Video Record Times

The table below shows the approximate total recording times using a memory card formatted within the a6400. The values may vary depending on the shooting conditions and the type of memory card used.

File Format	8 GB	32 GB	64 GB	256 GB
XAVC S 4K 30p 100M/25p 100M	9 min	35 min	1 h 15 min	5 h 15 min
XAVC S 4K 30p 60M/25p 60M	10 min	1 h	2 h 5 min	8 h 35 min
XAVC S 4K 24p 100M	9 min	35 min	1 h 15 min	5 h 15 min
XAVC S 4K 24p 60M	10 min	1 h	2 h 5 min	8 h 35 min
XAVC S HD 120p 100M/100p 100M	9 min	35 min	1 h 15 min	5 h 15 min
XAVC S HD 120p 60M/100p 60M	10 min	1 h	2 h 5 min	8 h 35 min
XAVC S HD 60p 50M/50p 50M	15 min	1 h 15 min	2 h 35 min	10 h 25 min
XAVC S HD 60p 25M/50p 25M	30 min	2 h 25 min	5 h	20 h 10 min
XAVC S HD 30p 50M/25p 50M	15 min	1 h 15 min	2 h 35 min	10 h 25 min
XAVC S HD 30p 16M/25p 16M	50 min	3 h 50 min	7 h 45 min	31 h 30 min
XAVC S HD 24p 50M	15 min	1 h 15 min	2 h 35 min	10 h 25 min
AVCHD 60i 24M(FX)/50i 24M(FX)	40 min	2 h 55 min	6 h	24 h 15 min
AVCHD 60i 17M(FH)/50i 17M(FH)	55 min	4 h 5 min	8 h 15 min	33 h 15 min

The duration of time available for movie recording varies depending on the file format/recording settings for movies, memory card, ambient temperature, Wi-Fi network environment, condition of the camera before you start recording, and condition of the charging of the battery.

The maximum continuous recording time for a single movie shooting session is approximately 13 hours (a product specification limit).

Best Memory Cards for 4k Video

The Sony a6400 supports a maximum of 100Mbps 4k video which is around 12.5 MB/s.

Any memory cards that are rated v30, v60, v90 card will work perfectly for shooting 4k video.

Cards that are 32GB and smaller are labelled as SDHC memory cards. These are formatted to 32-bit and video files will be broken-up into 4GB chunks. This means extra work in post to put all of these files together.

Cards that are 64GB and larger in capacity are labelled as SDXC cards, these are formatted with a 64-bit file system and your files will not be broken up into smaller chunks.

For video I’d recommend 64GB or larger SDXC cards. I’d recommend a card like the SanDisk Extreme PRO 128GB SDXC Memory Card.

UHS-I vs UHS-II

UHS-I SD cards have write speeds up to around 100MB/s and read speeds of around 170MB/s. UHS-II compatible cards increase this speed by adding a second row of contacts to the card, these cards are now capable of writing and reading up to around 300MB/s.

Unfortunately the Sony a6400 only supports the slower UHS-I SD cards. UHS-II SD cards will actually work, but they default to USH-I speeds in-camera, so you are wasting your money if you buy these.

The only benefit to using them is if you use a UHS-II card reader, you can then copy the files to your computer a lot faster.

FAQs

Summary

The Sony a6400 has a pretty slow in-camera write speed of around 40MB/s.

In my Sony a7III Memory Card Tests I tested the same UHS-I cards and the SanDisk Extreme Pro UHS-I (170/90) had an in-camera write speed of around 70MB/s when shooting compressed RAW.

For whatever reason Sony has restricted the potential of the UHS-I bus in the a6400, as it’s definitely capable of writing much faster than it is.

For this reason you don’t need the fastest memory cards since you will not be able to take advantage of them in the a6400. It’s also why you won’t see a big difference in write speed between the 6 cards that I tested.

With that said, it’s hard to go wrong with the SanDisk Extreme Pro UHS-I (170/90) that comes out on top in my tests. A 64GB card now costs around $20 US which is considerably less than this size of card cost only a few years back. If you shoot 4k video then this card is also v30 rated so you won’t have any issues here.

If you change your camera in the future to a model that supports faster write speeds then you’ll also have a very good SD card ready to go.

A 64GB card will be suitable for most purposes. I’d only recommend going larger if you shoot a lot of continuous bursts or 4K video.

Please don’t be tempted by the faster UHS-II SD cards. Although they work in the a6400 they will default to UHS-I speeds so you will be throwing your money away since they cost considerably more than UHS-I SD cards.

No matter which SD card you decide to go with, you’ll definitely find the Beeway SD Card holder very useful. It holds 12 SD/SDHC/SDXC cards and 12 MicroSD cards perfectly in place. The case is water resistant and very strong. It also includes a small bag and a carabiner. I own a couple of these myself and my memory cards don’t go anywhere without them.

If you have found this article helpful please consider taking a look at some of my additional Sony a6400 articles.

Sony a6400 Resources