A 35 mm lens on an APS-C camera frames like a 52 mm lens on full frame.
How to use the Crop Factor and Equivalent Focal Length Calculator
- Focal length
- Aperture f-number
- Sensor
Results update as you type, and every field accepts the units shown in its menu.
How it works
The crop factor is the ratio of the full-frame diagonal (43.3 mm) to the sensor diagonal.
Inputs explained
| Field | What to enter |
|---|---|
| Focal length | In mm |
| Aperture f-number | A number |
| Sensor | Choose one: APS-C Nikon/Sony/Fuji (1.5×), APS-C Canon (1.6×), Micro Four Thirds (2.0×), 1-inch (2.7×) … |
What each result means
- Equivalent focal length = [Focal length]×[Sensor]
- Equivalent aperture (depth of field) = [Aperture f-number]×[Sensor]
- Diagonal field of view = deg(2×atan(43.27÷(2×[Focal length]×[Sensor])))
Example values
How the main result changes when Focal length changes and everything else stays at the example values above:
| Focal length (mm) | Equivalent focal length (mm) |
|---|---|
| 17.5 | 26.3 |
| 26.25 | 39.4 |
| 35 | 52.5 |
| 43.75 | 65.6 |
| 52.5 | 78.8 |
| 70 | 105 |
Formula
Equivalent focal length = focal length × crop factorEquivalent aperture (DOF) = f-number × crop factorWorked example
Inputs — Focal length: 35 mm; Aperture f-number: 1.8; Sensor: APS-C Nikon/Sony/Fuji (1.5×).
Results — Equivalent focal length = 52.5 mm; Equivalent aperture (depth of field) = 2.7; Diagonal field of view = 44.8 °.
Frequently asked questions
Does crop factor change exposure?
No; f/1.8 gives the same exposure on any sensor. It changes depth of field equivalence.
What is “normal” focal length?
About 43–50 mm full-frame equivalent.
What formula does the Crop Factor and Equivalent Focal Length Calculator use?
Equivalent focal length = focal length × crop factor.