# Crop Factor and Equivalent Focal Length Calculator

URL: https://speedycalculator.com/calculators/other/equivalent-focal-length/
Last updated: 2026-10-25

> The crop factor calculator converts a lens’s focal length and aperture to their full-frame equivalents for APS-C, Micro Four Thirds and other sensor sizes, and gives the field of view.

## Inputs

- Focal length (mm)
- Aperture f-number
- Sensor

## Results

- Equivalent focal length
- Equivalent aperture (depth of field)
- Diagonal field of view

## Formula

```
Equivalent focal length = focal length × crop factor
Equivalent aperture (DOF) = f-number × crop factor
```

## Explanation

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

FieldWhat to enterFocal lengthIn mmAperture f-numberA numberSensorChoose 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)17.526.326.2539.43552.543.7565.652.578.870105

## Worked 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 °.

## FAQ

**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.