Crop Factor Calculator — 35 mm Equivalent Focal Length
Enter your sensor size (or choose a preset) and your lens focal length to get the crop factor and the 35 mm equivalent focal length — so you know exactly how your lens compares to full-frame references.
Camera sensor
mm
Ratio of full-frame diagonal to this sensor's diagonal
- 1
Full-frame diagonal
√(36² + 24²) = 43.27The reference diagonal of the 35 mm full-frame sensor (36 × 24 mm). - 2
Sensor diagonal
√(22.2² + 14.8²) = 26.68 - 3
Crop factor
43.27 ÷ 26.68 = 1.62
How does this calculator work?
Crop factor = 43.27 mm ÷ sensor diagonal. Multiply your focal length by the crop factor to get the 35 mm equivalent. APS-C Canon ≈ 1.6×, APS-C Nikon/Sony ≈ 1.5×, Micro Four Thirds = 2×. A 50 mm lens on an APS-C Canon behaves like an 81 mm lens on full frame.
Formula
How this is calculated
The crop factor compares a camera sensor's diagonal to the diagonal of a 35 mm full-frame sensor (36 × 24 mm, diagonal ≈ 43.27 mm). A smaller sensor "crops" the image circle that the lens projects, effectively multiplying the angle-of-view-narrowing effect as if you used a longer focal length on a full-frame camera. The formula is: crop factor = 43.27 / sensor_diagonal.
Multiplying your actual focal length by the crop factor gives the "35 mm equivalent" focal length — the full-frame focal length that would produce the same field of view. A 50 mm lens on an APS-C Canon body (crop factor ≈ 1.62) behaves like an 81 mm portrait telephoto would on a full-frame camera. Conversely, to match a wide 24 mm full-frame view on a Micro Four Thirds body (crop factor = 2×), you need a 12 mm lens.
The crop factor does not affect depth of field in the same ratio — to get equivalent bokeh you also need to open the aperture by the crop factor (e.g., f/1.8 on MFT ≈ f/3.6 on full frame). Sensor dimensions in this calculator follow manufacturer-published specifications; real production tolerances can cause minor variation.
Frequently asked questions
A higher crop factor means the sensor is smaller relative to full frame. A smaller sensor crops more of the lens image circle, making your lens behave like a longer (more zoomed-in) focal length. This benefits telephoto reach but makes wide-angle photography harder, and generally smaller sensors collect less light per pixel at the same aperture.
Yes. Many cameras use a crop region of the sensor for video, which can add an additional crop factor on top of the sensor's own crop factor. Check your camera's manual for the exact video crop applied in each mode.
In terms of field of view, yes — a 1.5× crop factor narrows the field of view by 1.5×, equivalent to using a 1.5× longer lens. However, the image is not optically magnified; the lens forms the same image circle, and the sensor simply uses a smaller portion of it.
Also known as
TG we-Calculate Editorial Team. (2026). Crop Factor Calculator — 35 mm Equivalent Focal Length [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/crop-factor-calculator
TG we-Calculate Editorial Team. "Crop Factor Calculator — 35 mm Equivalent Focal Length." TG we-Calculate. 2026. https://we-calculate.com/calculator/crop-factor-calculator.
TG we-Calculate Editorial Team, "Crop Factor Calculator — 35 mm Equivalent Focal Length," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/crop-factor-calculator
@misc{wecalculate_crop_factor_calculator, title = {Crop Factor Calculator — 35 mm Equivalent Focal Length}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/crop-factor-calculator}}, year = {2026}, note = {TG we-Calculate} }
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