Crop Factor Calculator

Lens focal lengths are usually compared as if every camera had a full-frame sensor of 36 × 24 mm. Smaller sensors see a narrower slice of the same image, so a lens frames as if it were longer. The ratio between the sensor diagonals is the crop factor. This calculator converts focal length and aperture into full-frame equivalents and shows the actual angle of view.

Sensors compared

The full-frame diagonal is about 43.3 mm. APS-C sensors from Nikon, Sony and Fujifilm, at 23.5 × 15.6 mm, give a crop factor of about 1.53; Canon’s slightly smaller APS-C about 1.61. Micro Four Thirds is exactly 2.0, 1-inch compact sensors about 2.7, and a typical modern phone main camera around 3.5. Medium format 44 × 33 mm is larger than full frame, with a factor of about 0.79, so lenses frame wider than their number suggests.

Equivalent focal length

Multiply the real focal length by the crop factor to get the full-frame equivalent. A 35 mm lens on Nikon APS-C frames like about 54 mm, close to a classic normal lens. A 12 mm lens on Micro Four Thirds frames like 24 mm, a typical wide-angle. A phone’s 6.9 mm main lens frames like about 24 mm.

Angle of view

The calculator also gives the diagonal angle of view and the horizontal and vertical angles. Those are the actual numbers that describe how much of the scene the camera sees, useful for planning architecture, astro and video shots, and for matching cameras in a multi-camera setup. The angles assume focus at infinity; close focusing narrows them slightly.

Equivalent aperture

At the same framing and viewing size, a smaller sensor gives more depth of field. Multiplying the f-number by the crop factor gives the full-frame aperture with the same depth of field and similar overall image noise: f/1.8 on Micro Four Thirds looks like f/3.6 on full frame in background blur. That explains why phones need computational blur for portrait mode.

What crop factor does not change

Exposure stays the same. An f/2.8 lens gives the same brightness and needs the same shutter speed on every sensor. The focal length itself does not change either, nor does perspective, which depends only on where you stand.

Choosing lenses for a smaller sensor

If you know a focal length you love on full frame, divide it by the crop factor to find its equivalent on your camera. A 35 mm full-frame look needs about 23 mm on APS-C and 17.5 mm on Micro Four Thirds.

Using it with other calculators

The Depth of Field Calculator uses the real focal length and the sensor size directly, so enter real values there. For star photography, crop factor affects how long stars stay sharp; the Star Trail Calculator handles that.

Video and crop modes

Many cameras crop the sensor further in 4K or high-frame-rate video, or offer an APS-C mode on full-frame bodies. Multiply the crop factors together: a 1.5× video crop on an APS-C camera gives about 2.3× overall. Check the camera manual for the exact video crop.

Related tools

For close-ups and magnification, use the Macro Extension Calculator. Plan light direction for a chosen angle of view with the Sun Angle Calculator.