Card Capacity Sheet
Frames follow from resolution and format. Video is what actually fills the card.
BFCBrilliance · bfcbrilliance.com/tools/photo-storage-capacity-calculator
The arithmetic
- FRAME SIZE
- megapixels x MB per megapixel
- Uncompressed RAW 14-bit
- 1.75 MB per MP — bit depth ÷ 8
- Compressed RAW
- about 1.1 MB per MP
- JPEG fine
- about 0.3 MB per MP — an AVERAGE
- 24 MP compressed RAW
- about 26 MB a frame
- VIDEO PER HOUR
- Mbps x 3600 ÷ 8000 GB
- 4K at 100 Mbps
- 45 GB an hour
- ⚠ 30 min of 4K
- 22.5 GB — about 850 RAW frames
- ⚠ Burst length
- is WRITE SPEED, not capacity
Cards and shoots
| Shoot | Card GB | Format | Frame MB | Video min | Frames left |
|---|---|---|---|---|---|
This shoot
- Shoot
- Date
- Card size
- Camera MP
- Format
- FRAME SIZE MB
- Video minutes
- Video bitrate
- VIDEO GB
- SPACE LEFT
- FRAMES THAT FIT
- Spare cards packed
- Offloaded and verified?
Before a shoot
- Video subtracted from the card FIRST — it dominates everything
- RAW+JPEG checked — if on, both files are being written
- Card's sustained WRITE speed checked against the video mode
- Spare cards packed, rather than relying on one large one
- Previous shoot offloaded AND verified before reformatting
- Formatted in the camera, not on a computer
- Battery life considered alongside card capacity
- Buffer depth understood if you shoot long bursts
Video and stills are not comparable
Half an hour of 4K at 100 Mbps takes 22.5 GB — about what 850 compressed RAW frames from a 24 MP camera take. One minute of video costs roughly 28 photographs. If any video is going on the card, it decides the answer and the stills are the remainder, which is why this sheet subtracts it first.
Speed and capacity are different specifications
A card with plenty of room can still stop a burst dead, or refuse a 4K mode, if its sustained write speed is too low. Capacity is how much it holds; speed is how fast it accepts data. They feel identical when you hit them and they have nothing to do with each other — check both before a shoot that matters.