Free calculator
Focal Length Match Calculator
A 50mm lens on full frame frames like a 34.6mm on Super 35: the crop factor between them is 1.45. Enter the lens and the two sensor widths to find the focal length that gives the same horizontal view on the other camera.
Free, no sign-up. Runs in your browser.
Built on the same formulas as the Focal Length Match Calculator in the CineMath app. Save, share and get the Pro tools in the app.
How it works
equivalent = focal length × (target width ÷ original width)Scaling the focal length by the ratio of the sensor widths keeps the same horizontal angle of view.
Where
- original width
- recorded width on the camera the lens is on now(mm)
- target width
- recorded width on the camera you are matching to(mm)
crop factor = original width ÷ target widthBetween your two cameras, not against full frame unless the original is 36 mm wide. Above 1 the target sees less; below 1 it sees more.
Matching more than the framing
The equivalent focal length matches the angle of view. Perspective comes from where the camera stands, so keep the same camera position as well. Depth of field differs at the same stop, and the background blur with it; the depth of field calculator gives each format's figures when you enter its lens and format.
Worked example
A 35mm on Super 35, matched on full frame
- equivalent = 35 × (36 ÷ 24.89) = 50.6 mm
- crop factor = 24.89 ÷ 36 = 0.69×
- horizontal angle, both = 2 × atan(24.89 ÷ 70) = 39.1°
Use a 50mm on the full-frame camera to match a 35mm on Super 35.
Quick reference
Full-frame focal lengths matched on smaller sensors (by width)
| On full frame | Super 35 (24.89 mm) | APS-C (23.6 mm) | Micro Four Thirds (17.3 mm) |
|---|---|---|---|
| 18 mm | 12.4 mm | 11.8 mm | 8.7 mm |
| 24 mm | 16.6 mm | 15.7 mm | 11.5 mm |
| 35 mm | 24.2 mm | 22.9 mm | 16.8 mm |
| 50 mm | 34.6 mm | 32.8 mm | 24.0 mm |
| 85 mm | 58.8 mm | 55.7 mm | 40.8 mm |
| 135 mm | 93.3 mm | 88.5 mm | 64.9 mm |
Save, share and get the Pro tools in the CineMath app
CineMath is a free download for iPhone, iPad and Mac, with this calculator built in. In version 1.3, coming soon to the App Store, CineMath Professional saves calculations to your history, shares them as links, and adds the Camera Database and Data Planning.
Questions
What is a crop factor?
The ratio between two sensor sizes. Super 35 at 24.89 mm wide has a crop factor of 1.45 against full frame’s 36 mm, so a lens on Super 35 frames like one 1.45 times longer on full frame: a 35mm looks like a 50.6mm.
Should I match on the width or the diagonal?
This calculator matches width, which keeps the horizontal framing, and suits film and video. Photographers often quote a diagonal crop factor; when the aspect ratios differ the two disagree. Super 35 at 24.89 × 18.66 mm is 1.45 by width but 1.39 by diagonal against 36 × 24 mm.
Does the matched lens give the same depth of field?
No. At the same stop, the smaller format holds more depth of field for the same framing. For a similar look, open the smaller format up by the crop factor: f/2.8 on full frame is close to f/2 on Super 35 (2.8 ÷ 1.45 = 1.9). Exposure does not change with the format.
Why use the recorded width rather than the sensor size?
Many cameras record less than the whole sensor in some modes, such as 16:9 or a crop mode for a smaller lens. The view depends on the area recorded, so enter the width of the mode you shoot. The sensor size chart lists widths by mode.
What is the Micro Four Thirds equivalent of an 85mm?
By width, 85 × 17.3 ÷ 36 = 40.8 mm, so a 40mm or 42.5mm lens on Micro Four Thirds frames like an 85mm on full frame.