Crop Factor Calculator

Crop sensors 'zoom in' — find the full-frame equivalent of a lens.

How the Math Works

The Crop Factor Calculator uses the formula equivalent focal length = focal length × crop factor to determine how a lens's field of view compares to a full-frame camera. Crop factor is a ratio representing the relative size of an image sensor compared to a 35mm full-frame sensor. For example, an APS-C sensor with a crop factor of 1.6 means a 50mm lens on that camera will have the same field of view as a 80mm lens (50 × 1.6) on a full-frame camera. This mathematical adjustment standardizes focal length comparisons across different sensor sizes.

Practical Applications

To use this calculator, multiply your lens's actual focal length by your camera's crop factor (found in your camera's specifications). For instance, a 35mm lens on a Micro Four Thirds camera (crop factor 2.0) becomes 70mm equivalent, while the same lens on an APS-C camera (crop factor 1.5) becomes 52.5mm equivalent. This helps photographers select lenses that achieve desired compositions, understand depth of field differences, or match the field of view from their previous full-frame setups when upgrading or switching camera systems.

Day-to-Day Use

This calculation simplifies everyday photography decisions by bridging the gap between different camera systems. Whether comparing gear, renting equipment, or choosing your first lens, knowing the full-frame equivalent helps predict how scenes will frame and what perspective you'll capture. It also aids in understanding creative effects—like realizing a 24mm lens on a crop sensor (1.5x) provides a narrower view than expected, requiring adjustment in shooting technique or subject distance to achieve intended compositions.

Worked example

35 mm × 1.5 → 52.5 mm equivalent.

FAQ