What is crop factor?
Crop factor describes how much smaller a camera sensor is compared to a traditional 35mm full-frame sensor. It’s calculated by dividing the diagonal measurement of a full-frame sensor (43.27mm) by the diagonal measurement of your camera’s actual sensor.
Formula used: Crop Factor = Full-Frame Diagonal (43.27mm) ÷ Your Sensor Diagonal, where sensor diagonal is found using the Pythagorean theorem from sensor width and height. A larger crop factor means a smaller sensor.
- Common examples: APS-C sensors (about 23.5mm x 15.6mm) have a crop factor near 1.5x; Micro Four Thirds sensors have a crop factor of 2x.
- To find how a lens behaves compared to full frame, multiply its actual focal length by the crop factor to get the "full-frame equivalent" focal length and field of view.
This tool is for general photography reference and planning purposes; exact sensor dimensions vary slightly by manufacturer.
Last reviewed August 2026