Crop Factor Calculator
Fill in the values and the answer updates as you type.
How the Crop Factor Calculator works
Crop factor = full-frame diagonal (43.27 mm) ÷ sensor diagonal. Multiply focal length and f-number by it to find the full-frame lens that gives the same field of view and depth of field. The lens still lets in the same light per area, so the equivalent aperture does not change exposure. Common values: APS-C about 1.5, Micro Four Thirds 2.0. Example: A 23.5 × 15.6 mm sensor has a crop factor of 1.53, so a 35 mm f/1.8 lens behaves like a 53.7 mm f/2.8 lens on full frame.
Inputs and results
The Crop Factor Calculator takes 4 inputs and gives 4 results.
What you enter
- Sensor width (mm) — starts at 23.5.
- Sensor height (mm) — starts at 15.6.
- Lens focal length (mm) — starts at 35.
- Lens aperture (f-number) (f/) — starts at 1.8.
What you get
- Crop factor
- Equivalent focal length (mm)
- Equivalent aperture (f-number)
- Sensor diagonal (mm)
Example: Crop Factor Calculator with the starting values
With sensor width 23.5 mm, sensor height 15.6 mm, lens focal length 35 mm and lens aperture (f-number) 1.8 f/, the calculator returns:
| Crop factor | 1.53 |
|---|---|
| Equivalent focal length (mm) | 53.7 |
| Equivalent aperture (f-number) | 2.8 |
| Sensor diagonal (mm) | 28.2 |
Change any value above and the results update straight away.
Crop Factor Calculator FAQ
How do I use the Crop Factor Calculator?
Enter sensor width, sensor height, lens focal length and lens aperture (f-number) in the fields, then read crop factor, equivalent focal length (mm), equivalent aperture (f-number) and sensor diagonal (mm) in the result panel. The answer updates as you type, and you can press Calculate or Enter to refresh it. Use “Copy link” to share your exact numbers with someone else.
What does the Crop Factor Calculator calculate?
Crop factor and full-frame equivalent focal length and aperture. It returns crop factor, equivalent focal length (mm), equivalent aperture (f-number) and sensor diagonal (mm) from the 4 values you provide.
What values does the Crop Factor Calculator start with?
It opens with sensor width 23.5 mm, sensor height 15.6 mm, lens focal length 35 mm and lens aperture (f-number) 1.8 f/ so you can see a working result straight away. Replace them with your own numbers, or press Reset to return to these starting values.
Is the Crop Factor Calculator free and private?
Yes. It is free, needs no account, and runs in your browser, so nothing you type is sent to or stored on our servers. See the Privacy Policy for details.
Can I rely on the Crop Factor Calculator for important decisions?
Treat the result as a well-rounded estimate. Real situations often have details a general calculator cannot know, so confirm important decisions with a qualified professional. See the Disclaimer for more.