Film formats and camera sensor sizes
A 35 mm film frame measures 24 × 36 mm, and a full-frame digital sensor is exactly the same size. Smaller sensors such as APS-C (about 23.5 × 15.6 mm) or Micro Four Thirds (17.3 × 13 mm) have a crop factor of 1.5 to 2.
Contents of this page
Film formats
| Format | Frame size | Film | Aspect ratio |
|---|---|---|---|
| 35 mm (full frame) | 24 × 36 mm | type 135 | 3:2 |
| Half frame | 18 × 24 mm | type 135 | 4:3 |
| Medium format 6 × 4.5 | about 56 × 41.5 mm | 120 roll film | 4:3 |
| Medium format 6 × 6 | about 56 × 56 mm | 120 roll film | 1:1 |
| Medium format 6 × 7 | about 56 × 69.5 mm | 120 roll film | about 5:4 |
| Medium format 6 × 9 | about 56 × 84 mm | 120 roll film | 3:2 |
| Large format 4 × 5 in | about 102 × 127 mm | sheet film | 5:4 |
| Large format 8 × 10 in | about 203 × 254 mm | sheet film | 5:4 |
Medium format names are nominal sizes in centimetres. The actual frame is slightly smaller, because the film needs room at the edges for spacing and transport. In large format, each picture is exposed on its own sheet of film, so there is no roll at all.
The larger the negative, the less it has to be enlarged for a print. A 6 × 7 negative has about 4.5 times the area of a 35 mm negative, and the grain in the print is correspondingly finer.
Digital sensor sizes
| Sensor | Size (approx.) | Crop factor | Typical cameras |
|---|---|---|---|
| Digital medium format | 44 × 33 mm | 0.79 | Fujifilm GFX, Hasselblad X |
| Full frame | 36 × 24 mm | 1.0 | professional and high-end mirrorless cameras |
| APS-C | 23.5 × 15.6 mm | 1.5 | many mirrorless cameras and DSLRs |
| APS-C (Canon) | 22.3 × 14.9 mm | 1.6 | Canon models with APS-C |
| Micro Four Thirds | 17.3 × 13 mm | 2.0 | OM System, Panasonic |
| 1 inch | 13.2 × 8.8 mm | 2.7 | premium compacts, drones |
The crop factor is the ratio of the sensor diagonal to that of 35 mm film. It tells you how much the angle of view is cropped compared with full frame. A 50 mm lens on APS-C gives the same view as a 75 mm lens on full frame.
The name “1 inch” is misleading, by the way. It dates back to television camera tubes and has little to do with the actual sensor size. The diagonal of a 1-inch sensor is only about 16 mm.
How large can I print a digital photo?
What counts is the pixel count, not the sensor size. At 300 dpi:
| Camera | Pixels | Print size at 300 dpi | At 150 dpi |
|---|---|---|---|
| 12 MP (smartphone) | 4032 × 3024 | 34.1 × 25.6 cm | 68.3 × 51.2 cm |
| 24 MP | 6000 × 4000 | 50.8 × 33.9 cm | 101.6 × 67.7 cm |
| 45 MP | 8192 × 5464 | 69.4 × 46.3 cm | 138.7 × 92.5 cm |
| 100 MP | 11,648 × 8736 | 98.6 × 74 cm | 197.2 × 147.9 cm |
So a 24-megapixel image is enough for about A3 at 300 dpi, or an A1 poster at 150 dpi. For your own values, use the pixels to cm converter.
Frequently asked questions
How big is 35 mm film?
A frame measures 24 × 36 mm, with an aspect ratio of 3:2.
How big is an APS-C sensor?
About 23.5 × 15.6 mm. Canon’s version is about 22.3 × 14.9 mm.
What is crop factor?
The ratio of a sensor’s diagonal to that of 35 mm film. About 1.5 for APS-C and 2 for Micro Four Thirds.
How big is a full-frame sensor?
36 × 24 mm, exactly the size of a 35 mm negative.