Crop Factor Calculator (Equivalent Focal Length & Aperture)
Convert a lens's focal length and aperture to their full-frame equivalents for APS-C, Micro Four Thirds, 1-inch and medium format sensors, and see the horizontal angle of view.
Last updated: May 2026
Full-frame equivalent focal length
75 mm
Formula below · 3 sources (dpreview.com, cambridgeincolour.com, Wikipedia)
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About this calculator
The crop factor is the ratio of a full-frame (36 × 24 mm) sensor's diagonal, 43.3 mm, to your sensor's diagonal. Multiplying by it converts to the full-frame lens that would give the same picture:
equivalent focal length = focal length × crop factor equivalent aperture = f-number × crop factor
The equivalent focal length gives the same angle of view. The equivalent aperture gives the same depth of field and the same total light gathered over the frame (and so similar noise at the same output size). It does not change exposure: f/1.8 is f/1.8 for setting shutter speed and ISO on any camera.
The angle of view uses the full-frame equivalent: horizontal = 2 × atan(36 ÷ (2 × equivalent focal length)), diagonal with 43.27 mm.
Crop factors differ slightly between models (Canon APS-C is 1.6×, Nikon, Sony and Fujifilm 1.5×, Micro Four Thirds 2.0× on the diagonal); check your camera's sensor size for exact work.
How to use
Enter the focal length printed on the lens, choose your sensor, and enter the aperture. Example (the defaults): a 50 mm f/1.8 lens on a 1.5× APS-C camera frames like 50 × 1.5 = 75 mm on full frame, with the depth of field of f/2.7, and a horizontal angle of view of 2 × atan(36 ÷ 150) = 27.0°. Example 2: a 12–40 mm f/2.8 zoom on Micro Four Thirds (2×) is a 24–80 mm equivalent with f/5.6-equivalent depth of field. Example 3: an 80 mm lens on 44 × 33 mm medium format (0.79×) frames like 63 mm on full frame.
Frequently asked questions
Does a crop sensor make my lens longer?
No. The focal length is a property of the lens. A smaller sensor records only the middle of the image, so the picture looks like it came from a longer lens on full frame. That is why it is called a crop factor.
Do I need to multiply the aperture for exposure?
No. Exposure (shutter speed and ISO for a given brightness) depends on the f-number alone, so f/2.8 needs the same settings on every format. Multiply the aperture only to compare depth of field and background blur, or total light and noise at the same print size.
What is the crop factor of my phone?
Phone main cameras have tiny sensors, often with crop factors of 3–7, so phones and their apps usually quote the 35 mm equivalent focal length (for example 24 mm or 26 mm) directly. Use that number as the equivalent focal length.
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