How big is a photo?
A photo file’s size depends mainly on the number of pixels and the file format.
- Uncompressed RAW stores each pixel’s sensor value, usually at 12 or 14 bits: 24 megapixels × 14 bits ÷ 8 = 42 MB.
- Lossless compressed RAW, the default on many cameras, is usually 60 to 70% of that.
- JPEG compresses heavily; a fine-quality JPEG averages about 0.3 to 0.4 MB per megapixel, depending on detail and noise.
- HEIF/HEIC, used by phones and newer cameras, is about half the size of JPEG at similar quality.
The calculator uses typical ratios per megapixel. Busy scenes such as foliage or high-ISO noise make files larger; plain skies make them smaller.
Example
A 24 MP camera shooting fine JPEGs makes files of about 8.4 MB. A 64 GB card, with 5% left free, holds about 7,200 photos. In uncompressed RAW the same card holds about 1,400.
| Format, 24 MP | Size per photo | Photos on 64 GB |
|---|---|---|
| HEIF | 4.8 MB | about 12,700 |
| JPEG fine | 8.4 MB | about 7,200 |
| RAW compressed | 29 MB | about 2,100 |
| RAW + JPEG | 37 MB | about 1,600 |
| RAW uncompressed | 42 MB | about 1,400 |
Pixel dimensions and print size
A 24 MP sensor in 3:2 format is 6,000 × 4,000 pixels. At 300 DPI, the usual standard for high-quality prints, that is 20 × 13.3 inches. Larger prints viewed from farther away look fine at 150 to 200 DPI.
Choosing a card
- Capacity: plan for a full day or trip without changing cards, plus margin.
- Speed: for bursts and 4K video, check the write speed (V30, V60, V90 for video; UHS-II for fast bursts).
- Backups: several medium cards spread the risk better than one huge card.
Storage at home
A photographer shooting 10,000 RAW files a year at 30 MB uses about 300 GB a year. Keep at least two copies, one of them off-site or in the cloud.