Best Memory Cards for the Sony FX3

You may not require the most expensive card for the Sony FX3, or perhaps you need more memory than you thought. This article has everything you need to decide.
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The Sony FX3 shares much in common with it’s sister camera, the Sony A7S III, internals and specs. But the FX3 is a Cinema camera first and only. But does it share the same memory card requirements?

The best two memory cards to use with the Sony FX3 are the Sony CEA-T 160GB (G Rough) CFExpress Card. For the SD Card I recommend the Sandisk Extreme 128GB.

Last update on 2024-07-17 / Affiliate links / Images from Amazon Product Advertising API

These two recommended cards are for general purpose requirements only. Everyone who uses the FX3 will have different use cases and so will require different size memory cards.

You may not need a 512GB card or maybe you only really need an 80GB card because you’re only using the FX3 as a B-cam. Either way let’s go over how much you can get with the right compatible cards.

Sony Alpha FX3 ILME-FX3 | Full-frame Cinema Line Camera
  • 4K full-frame sensor w/ 15+ stop dynamic range and high sensitivity
  • S-Cinetone for expressive cinematic look inspired by VENICE colorimetry

Last update on 2024-07-17 / Affiliate links / Images from Amazon Product Advertising API

Or maybe you need to record in the best format available, the highest bitrate or it must be SLOG to get the full dynamic range.

Choosing the Best Memory Card for the Sony FX3

Similar to the Sony A7S III the Sony FX3 can take two different cards in its two card slots, UHS-II SD cards and CFExpress Type A cards.

If you want a card that covers all formats and available modes on the Sony FX3 then you should choose a CFExpress Type A card.

However if your budget can’t accommodate this memory card format which is relatively new hence the cost, then you should choose a high spec SD card which would be a UHS-II V90 card which will cover the 600Mbps bitrate the FX3 is capable of.

A lot of articles waffle on taking ages to get to the answer, so now you have two recommendations, let’s get more specific, and find out the the card that’s right for you specifically.

Later on I explain SD cards and CFExpress cards in more detail, check it out later down the article.

How Much Video Can You Record to a Memory Card

As I previously mentioned, a CFExpress Type A card will cover all recording modes available on the FX3. 

They’re quite costly, but if you need the highest quality video this is the only option, so let’s calculate how much you can record to a CFExpress Type A card:

CFExpress Type A
Recording ModeCard SizeBitrateAvailable Time RecordingCompatible Card
XAVC HS/ 4K 59.94p/50p160GB200M85 MinutesCheck on Amazon
XAVC HS 4K 59.94/50p80GB200M40 MinutesCheck on Amazon
XAVC HS 4K 59.94p/50p 160GB150M110 MinutesCheck on Amazon
XAVC HS 4K 59.94p/50p 80GB150M55 MinutesCheck on Amazon
XAVC HS 4K 59.94p/50p 160GB100M170 MinutesCheck on Amazon
XAVC HS 4K 59.94p/50p 80GB100M80 MinutesCheck on Amazon
XAVC HS 4K 59.94p/50p160GB75M220 MinutesCheck on Amazon
XAVC HS 4K 59.94p/50p80GB75M100 MinutesCheck on Amazon
XAVC HS 4K 59.94p/50p160GB45M340 MinutesCheck on Amazon
XAVC HS 4K 59.94p/50p80GB45M160 MinutesCheck on Amazon
XAVC S 4K 59.94p/50p 160GB200M85 MinutesCheck on Amazon
XAVC S 4K 59.94p/50p 80GB200M40 MinutesCheck on Amazon
XAVC S 4K 59.94p/50p160GB150M110 MinutesCheck on Amazon
XAVC S 4K 59.94p/50p80GB150M55 MinutesCheck on Amazon
XAVC S HD 59.94p/50p160GB50M310 MinutesCheck on Amazon
XAVC S HD 59.94p/50p80GB50M150 MinutesCheck on Amazon
XAVC S-I 4K  59.94p/50p160GB25 MinutesCheck on Amazon
XAVC S-I 4K  59.94p/50p80GB10 MinutesCheck on Amazon
XAVC S-I HD 59.94p/50p160GB75 MinutesCheck on Amazon
XAVC S-I HD 59.94p/50p80GB35 MinutesCheck on Amazon

You can record much more to a UHS-II SD card, with the much larger capacities. However some recording modes will be unavailable.

As I mentioned, let’s now explain everything on the face of a memory card so you can read and understand what it is your card is capable of and what its limits are.

SD Cards Explained

So on the face of a SD card you will find symbols and numbers that represent the SD card’s various elements like read write speeds. 

By understanding these elements you can work out if the card will meet your requirements.


The only actual difference between these two are that they are two types of filing systems representing higher memory capacities.

The main thing to note is that the SDHC filing system cards hold a maximum of 32GB of storage. Whereas the SDXC filing system holds up to 2TB of storage.

However SDXC cards are only available up to 512GB of storage as of the time of the publication of this article.

Maximum Read Speeds

You will find that SD card manufactures do not disclose the information of their write speeds for their cards.

The top left of right number will usually represent the maximum achievable read speed.

Read speeds will be mainly of importance to photographers than videographers.

For video the number of relevance is the sustained speed. This is of most importance because when the sustained speed falls before the video bit rate (e.g. 200Mbps) there will be dropped frames, which obviously is unwanted.

Memory Capacity

The memory capacity is the most understandable number on the face of the SD card, which represents the storage capacity of that SD card in gigabytes.

Speed Class Rating

The remaining numbers on the right side of the SD card represent in various symbols the speed class rating of that particular SD card.

The letter C with a number enclosed inside which can be 2, 4, 6, or 10 is the minimum write speed. For example 2MBps is Class 2, 4MBps for Class 4 and so on.

This is the minimum rate and not the actual rate.

The letter U which will have a number inside the U, 1 or 3, represents the minimum sustained write speed of the card.

U1 represents 10MBps and U3 for 30MBps.

You’ll find a U3 card will cover most recording modes adequately.

U1 and Class 10 should cover most recording modes available on the FX3.

Bear in mind that confusingly U1 and Class 10 basically represent the same thing, both representing a minimum write speed of 10MBps.

Where the difference is that the U is designed for SD cards that employ the UHS-I or USH-II bus.

Older non-USH cards are not adequate really, maxing out at 25MBps. UHS-I cards, on the other hand, max out at 104MBps, but the UHS-II card will go all the way to 312MBps.

You can identify a UHS-II card by the second row of pins on the back of the card, which allows the card to write faster with more pins.

The V speed represents the same thing as the U number. The minimum sustained write speed in MBps.

CFExpress Type A

CFExpress Type A is a new card format. The come in a small variety of flavors, 160Gb, 128Gb, 80GB etc.

Sony MRWG2 CFexpress Card Reader
  • Compatible with CFexpress Type A and SDXC/SDHC (UHS-I and UHS-II) memory cards
  • SuperSpeed USB 10Gbps (USB 3.2 Gen 2) transfer speed via USB Type-C connector

Last update on 2024-07-17 / Affiliate links / Images from Amazon Product Advertising API

They offer maximum read speeds of 1700MBps, compared to 1500MBps for smaller cards.

There is less information on the CFExpress card, but the main numbers to look at are the memory capacity and write speed which is in the number within the film flapperboard.


If you’re building out your new system and buying these cards for the first time I have recommended, then you’ll need an SD card reader.

Check these out with the links.

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