πΈ Focal Length Converter
Convert focal lengths and find field of view across sensor formats.
Full Frame Equivalent
How to Use This Calculator
Enter your actual lens focal length and select the camera body (sensor size) you are using. The calculator instantly shows the full-frame equivalent focal length, the field of view in degrees, and a table of how wide the scene is at different shooting distances. This helps you visualize exactly what the lens will capture on your camera.
Enter the focal length printed on your lens barrel. This is the physical focal length: a 50mm lens on any camera is always 50mm.
Select your camera body from the sensor dropdown. An APS-C Canon body has a 1.6Γ crop, so a 50mm lens behaves like an 80mm in terms of framing.
Check the horizontal, vertical, and diagonal field of view angles. These tell you the angular extent of the scene you'll capture, useful for planning architectural shots or panorama sequences.
Use the field of view distance table to see how wide the scene is at different distances. At 10 meters with an 80mm equivalent, you capture about 4.5 meters of width.
Crop Factor Formula
The crop factor comes from dividing the full-frame sensor diagonal (43.27mm) by your sensor's diagonal. A lens's actual focal length never changes, but the portion of the image circle the smaller sensor captures is equivalent to what a longer lens would show on full frame. The field of view formula uses trigonometry to convert sensor size and focal length into an angle, which tells you exactly how much of the world the frame contains.
Real-World Examples
When You Need This
When switching between camera systems, or borrowing a friend's body, knowing the crop factor equivalent stops you from showing up with the wrong lens. If you normally shoot portraits on a 85mm full-frame lens and your second body is APS-C, a 50mm lens gets you the closest equivalent framing and perspective. Checking the equivalent focal length first saves you from packing the wrong glass on a trip.
Wide-angle users often find that the crop factor works against them. A 17mm lens on an APS-C camera behaves like a 27mm, which is useful but not truly wide. Understanding this ahead of time means you can invest in a 10mm or 12mm APS-C specific lens to get the ultra-wide look you want, rather than buying a 17mm and being disappointed by the field of view in real use. This calculator makes those lens buying decisions much clearer before you spend money.
Frequently Asked Questions
What is crop factor?
Crop factor (or focal length multiplier) compares a sensor size to 35mm full frame. APS-C sensors typically have a 1.5β1.6Γ crop factor, meaning a 50mm lens behaves like a 75β80mm on full frame.
What is full-frame equivalent focal length?
It's the focal length on a full-frame camera that gives the same field of view. Equivalent FL = actual FL Γ crop factor. A 35mm lens on APS-C (1.5Γ) = 52.5mm equivalent.
Does crop factor affect depth of field?
Yes β a cropped sensor effectively produces more depth of field. To match full-frame DOF on APS-C, open aperture by the crop factor (e.g., f/2.8 FF β f/1.8 on APS-C).
What is field of view (FOV)?
FOV is the angular extent of the scene captured. A 28mm full-frame lens has ~75Β° diagonal FOV. Longer focal lengths have narrower FOV; wider lenses have broader FOV.
Why do APS-C lenses not work on full-frame bodies?
APS-C lenses project a smaller image circle. On a full-frame sensor, the corners would be dark (vignetting) or the image circle wouldn't cover the sensor. Some FF bodies can use crop mode with APS-C lenses.