Camera
Crop Factor Calculator
Crop factor and effective focal length between sensor formats.
Runs entirely in your browser. Nothing is uploaded.
How to use
- Choose your sensor or film format.
- Set the focal length of the lens you are mounting.
- Set the aperture you plan to shoot at.
- Read the crop factor, the full-frame-equivalent focal length, and the equivalent aperture for depth of field.
Examples
- A 50mm on an APS-C body has a crop factor near 1.5, so it frames like a 75mm on full frame, tighter than you might expect.
- Micro Four Thirds has a 2x crop, turning a 25mm into a 50mm equivalent, which is why compact systems reach wide and tele with shorter lenses.
- A fast f/1.8 on a small sensor gives the depth of field of a slower aperture on full frame, useful when comparing how shallow two systems can really go.
Frequently asked questions
What is crop factor?
It is the ratio between a full-frame sensor diagonal and a smaller one. Multiply a lens focal length by the crop factor to see how it frames on the smaller sensor compared to full frame.
Does crop factor change the actual focal length?
No. A 50mm is always a 50mm optically. The sensor simply captures a smaller part of the image circle, so the field of view is narrower, which we describe as an equivalent focal length.
Why is there an equivalent aperture?
For matching framing, a smaller sensor gives more depth of field and gathers less total light at the same f-number. Multiplying the f-number by the crop factor shows the full-frame aperture that would look the same, which is handy for comparing systems.
