Memory cards for cameras are removable flash-storage devices that determine how many photos and how much video your camera can hold — and how fast it can shoot.
If you are shopping for a memory card for your camera, the main decisions come down to three things: which format your camera accepts, how much capacity you need, and whether the card is fast enough for your shooting style. Most cameras today use SD or CFexpress cards, but the right choice depends entirely on what your camera manual says. The table below lays out the specs that matter.
What Formats Do Camera Memory Cards Use?
Your camera’s slot determines the card format you can buy. The most common families are SD, CFexpress, and legacy CompactFlash. SD cards dominate consumer and prosumer cameras, while CFexpress Type B is used in many professional bodies for higher performance, especially at 4K and above.
A card may be physically compatible with a slot but run slower than its rating if the camera’s interface is older. Always check the manual before buying. And for a practical buying guide, see our roundup of top-rated DSLR memory cards.
Speed Classes: What Do the Numbers Mean?
Camera memory cards use speed classes that tell you the minimum sustained write speed, which is what matters most for burst shooting and video. Here is what the labels actually guarantee:
- Class 10 — minimum 10 MB/s sustained write. Fine for basic stills and standard video.
- U3 — minimum 30 MB/s sustained write. Required for 4K video on most cameras.
- V30, V60, V90 — minimum 30, 60, and 90 MB/s sustained write. V90 is the standard for high-bitrate 4K and 8K recording.
Cards also carry maximum read/write speeds in MB/s (e.g., 310 MB/s read, 305 MB/s write). Write speed is the critical metric for camera performance; read speed matters only when transferring files to a computer.
How to Match a Card to Your Camera
The fundamental rule is: check the camera’s manual for the supported card type, capacity ceiling, and minimum speed class. A fast card in a slow slot works at the slot’s speed, not the card’s. Key recommendations from current guidance include:
- For cameras with a single SD slot, a UHS-II V90 card like the SanDisk Extreme PRO UHS-II V90 (read up to 310 MB/s, write up to 305 MB/s) is a strong choice for 4K and burst work.
Do not mix up read and write speeds — write speed determines whether your camera can keep up with rapid shooting or video. Buy more capacity for high-megapixel stills and 8K video, which consume more space per shot.
| Format | Common Capacity Range | Speed Notes |
|---|---|---|
| SD / SDHC / SDXC | Up to 2TB (SDXC) | UHS-I up to 104 MB/s; UHS-II up to 312 MB/s; |
| CFexpress Type B | From 128GB and up | |
| CFast 2.0 | Less common today | Slower than CFexpress; found in some older pro cameras |
Common Mistakes and Care Tips
Buying by capacity only, ignoring write speed, and assuming an adapter makes a card fully compatible are the most frequent errors. Also, never delete files one by one in the camera; instead, download files to a computer or tablet, verify the backup, then format the card inside the camera’s setup menu. Treat memory cards as temporary working storage, not as your only archive copy.
FAQs
Can I use an SD card in a CFexpress slot?
No — the physical slots are different. Some cameras have dual slots (one for SD, one for CFexpress), but you cannot insert an SD card into a CFexpress slot without an adapter, and such adapters are not standard. Check the camera manual for supported types.
Is a faster card always better for my camera?
Only up to the speed your camera’s interface supports. A V90 SD card in a camera with a UHS-I slot will run at the slot’s maximum, around 104 MB/s. Buying a card rated above your camera’s ceiling offers no extra recording performance, though it can speed up file transfers to your computer with a compatible reader.
How do I check which memory card my camera needs?
Look in the camera manual’s specifications section. It lists the supported card format (e.g., SDXC, CFexpress Type B), the maximum capacity, and the minimum recommended speed class for video. Many manufacturers also publish this in the camera’s main menu under format options.
References & Sources
- Wikipedia. “Memory card.” General definition and format overview.
- Wikipedia. “SD card.” Speed class definitions, capacity ranges, and bus modes.
- Wirecutter / New York Times. “The Best SD Card.” Guidance on speed classes, card recommendations, and camera pairing.
Mo Maruf
I created WellFizz to bridge the gap between vague wellness advice and actionable solutions. My mission is simple: to decode the research and give you practical tools you can actually use.
Beyond the data, I am a passionate traveler. I believe that stepping away from the screen to explore new environments is essential for mental clarity and physical vitality.