Focal Length Equivalent Calculator
Convert any focal length between sensor formats — full frame, APS-C, Micro Four Thirds, medium format. Understand field of view across camera systems.
Calculator results are estimates based on simplified optical formulas. Actual results vary by lens, camera, and shooting conditions. Use these as starting points, not precise measurements.
Why Focal Length Equivalents Matter
Different camera systems use different sensor sizes, which means the same lens produces a different angle of view on each. A 50mm lens is considered a "normal" lens on full frame but becomes an 80mm portrait lens on APS-C. Understanding these conversions helps you choose the right lenses when switching systems or comparing gear recommendations across formats.
Field of View vs. Depth of Field
This calculator converts field of view only. Two "equivalent" setups will produce the same framing but different depth of field and bokeh. To get equivalent depth of field, you'd need to adjust aperture proportionally as well. A full-frame 85mm f/1.8 portrait setup would require an 85mm lens at roughly f/1.2 on APS-C to match both the framing and the background separation.
Common Equivalent Focal Lengths
| Full Frame | APS-C (1.5x) | APS-C (1.6x) | MFT (2x) |
|---|---|---|---|
| 24mm (wide) | 16mm | 15mm | 12mm |
| 35mm (wide-normal) | 23mm | 22mm | 17.5mm |
| 50mm (normal) | 33mm | 31mm | 25mm |
| 85mm (portrait) | 56mm | 53mm | 42.5mm |
| 135mm (telephoto) | 90mm | 84mm | 67.5mm |
| 200mm (telephoto) | 133mm | 125mm | 100mm |
Frequently Asked Questions
Why would I need to convert focal lengths between sensor formats?
If you're switching camera systems, renting a different body, or comparing gear across formats, focal length equivalents help you understand what angle of view you'll actually get. A lens that works as a normal lens on one system might be a portrait-length telephoto on another.
Does equivalent focal length mean the lenses are identical?
No. Equivalent focal length only describes the angle of view. A 35mm lens on a full-frame camera and a 23mm lens on an APS-C camera produce the same framing, but they are different optical designs with different minimum focus distances, distortion characteristics, and bokeh rendering.
What is the equivalent of 50mm on Micro Four Thirds?
On a Micro Four Thirds camera (2x crop factor), a 25mm lens provides the same field of view as a 50mm lens on full frame. To match 50mm exactly on MFT, you'd use a 25mm lens.