Find the full-frame equivalent of any lens
This crop factor calculator converts a lens between sensor sizes. Pick your sensor (APS-C, Micro Four Thirds, 1-inch, a phone or any custom size), enter the focal length, aperture and ISO, and it shows the crop factor, the 35 mm full-frame equivalent focal length, and the equivalent aperture and ISO that would give the same depth of field and total light.
A second sensor menu lets you compare any two formats directly, for example which Micro Four Thirds lens frames like a 35 mm lens on APS-C. The table underneath lists the equivalent focal length on every sensor in the list and downloads as a CSV file. Everything runs in your browser.
How to use the crop factor calculator
- Choose Your sensor, or type its width and height in millimetres from the camera’s specification page.
- Enter the focal length on the lens, plus the aperture and ISO you are using.
- Leave Compare with on full frame for the 35 mm equivalent, or pick another sensor.
- Read the equivalent focal length, aperture and ISO, or copy them with one click.
Crop Factor Calculator features
Any two sensors
Compare APS-C, Micro Four Thirds, 1″, medium format and small phone sensors in either direction.
Focal length, aperture and ISO
All three equivalents, not only the familiar focal length multiplier.
Reference table
Crop factor and equivalent focal length for 18 sensor formats, downloadable as CSV.
The crop factor formula
Crop factor is the diagonal of the 35 mm full-frame sensor (43.267 mm, from 36 × 24 mm) divided by the diagonal of your sensor. An APS-C sensor of 23.5 × 15.6 mm has a diagonal of 28.2 mm, so its crop factor is 1.53. Multiply the focal length by the crop factor to get the full-frame focal length with the same angle of view: 35 mm × 1.53 ≈ 53.7 mm.
The lens itself does not change. A 35 mm lens is 35 mm everywhere; the smaller sensor simply records the middle part of the image circle. Canon APS-C bodies use 22.3 × 14.8 mm (1.61×) and Micro Four Thirds is 17.3 × 13 mm (2.0×). Sizes are typical values from the Wikipedia “Image sensor format” table and makers’ specification pages, read on 24 October 2026; individual models differ slightly.
Why photographers use equivalents
Crop factor lets you compare kit across systems. If you love a 85 mm portrait lens on full frame, a 56 mm lens on a 1.5× body gives a very similar field of view, and a 42.5 mm lens on Micro Four Thirds does too. Travel and wildlife shooters use it the other way: a 300 mm lens on a 2× sensor reaches like a 600 mm lens on full frame, which is why small-sensor systems are popular for birding.
Remember the trade-off. A smaller sensor gives more depth of field at the same framing and aperture, and usually more noise in dim light. Neither is better in general; equivalence just helps you choose lenses that deliver the look you want.
Equivalent aperture and ISO
To match full-frame depth of field you also multiply the f-number by the crop factor, so 35 mm f/1.8 on APS-C looks like roughly 53.7 mm f/2.8 on full frame. Total light collected scales the same way, so ISO is multiplied by the crop factor squared. This is the “equivalence” idea described in Wikipedia’s Equivalence (photography) article.
Equivalent aperture is not an exposure setting. Your camera still meters at f/1.8, and the shutter speed needed for a correct exposure does not change. Equivalence only compares look: field of view, depth of field and noise for the same final image size.
| Format | Size (mm) | Crop factor |
|---|---|---|
| Full frame | 36 × 24 | 1.0 |
| APS-C (Sony, Nikon, Fujifilm) | 23.5 × 15.6 | 1.53 |
| APS-C (Canon) | 22.3 × 14.8 | 1.61 |
| Micro Four Thirds | 17.3 × 13.0 | 2.0 |
| 1″ type | 13.2 × 8.8 | 2.7 |
Crop Factor Calculator FAQ
What is the crop factor of APS-C?
About 1.5 for Sony, Nikon and Fujifilm (23.5 × 15.6 mm) and 1.6 for Canon (22.3 × 14.8 mm).
How do I convert a focal length to full-frame equivalent?
Multiply by the crop factor. A 50 mm lens on a 1.5× body frames like 75 mm on full frame; on Micro Four Thirds (2×) it frames like 100 mm.
Does a crop sensor make the lens longer?
No. It only crops the image, so the angle of view narrows. Optical properties such as perspective from a fixed position stay the same.
Is the equivalent aperture the real aperture?
No. Exposure still uses the marked f-number. The equivalent figure only predicts depth of field, as explained above.
Which crop factor do phones have?
Roughly 5 to 8 for typical 1/2.3″ to 1/1.3″ type sensors. Enter the exact width and height if you know them; phone makers usually quote a 35 mm equivalent directly.
Where can I check angle of view?
Use the camera FOV calculator for angles of view and scene width.