What is a 35mm equivalent focal length?

The 35mm equivalent (EFL) tells you what focal length on a full-frame (35mm film) camera would produce the same angle of view as your lens on its actual sensor. It is calculated as EFL = focal_length × crop_factor.

What crop factor does APS-C use?

Most APS-C sensors (Nikon, Sony, Pentax) use a crop factor of about 1.5×. Canon APS-C sensors are slightly smaller, giving roughly 1.6×. A 35 mm lens on a 1.5× APS-C camera has a 52.5 mm full-frame equivalent.

What is the crop factor for Micro Four Thirds?

Micro Four Thirds (MFT) has a crop factor of 2×. A 25 mm lens on MFT is equivalent to a 50 mm lens on a full-frame camera.

Does the crop factor change the actual focal length of the lens?

No. The physical focal length printed on the lens does not change. Crop factor only describes how the smaller sensor captures a narrower portion of the image circle, making the lens appear to reach farther (a telephoto effect).

What crop factor do medium format cameras have?

Medium format sensors are larger than full frame, so they have a crop factor below 1×. For example, a 44×33 mm medium format sensor has a crop factor of about 0.79×, meaning lenses produce a wider field of view than on full frame.

How do I find the angle of view from the EFL?

The diagonal angle of view is: AOV = 2 × arctan(43.27 / (2 × EFL)). This calculator computes that automatically and shows it alongside the EFL result.

Focal Length Equivalent Calculator

Name: Focal Length Equivalent Calculator
Availability: InStock
Author: Nham Vu

Enter your lens focal length and crop factor (or pick a sensor format) to instantly get its 35mm full-frame equivalent focal length.

Lens & Sensor Settings

Lens focal length (mm)

Sensor format

Crop factor

Common crop factors

Full frame1.0× APS-C (Nikon/Sony)1.5× APS-C (Canon)1.6× Micro Four Thirds2.0× 1-inch sensor2.7× 1/2.3-inch compact5.6×

Equivalent Focal Length

Enter a focal length and select a sensor format (or type a crop factor) to see results.

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Summary

Enter your lens focal length and crop factor (or pick a sensor format) to instantly get its 35mm full-frame equivalent focal length.

How it works

Select a sensor format preset (APS-C Canon, APS-C Nikon/Sony, Micro Four Thirds, 1-inch, medium format) or type a custom crop factor directly.
Enter your lens focal length in millimeters.
The equivalent focal length is calculated as: EFL = focal_length × crop_factor.
The angle of view is derived from the EFL using the standard 35mm frame diagonal (43.27 mm) and the arctan formula.
Results update live as you type — no button press needed.

Use cases

Find out how a 50 mm lens "sees" on an APS-C body before buying.
Choose the right native focal length to match a target full-frame perspective.
Compare how the same lens behaves on different crop-sensor bodies.
Plan portrait, landscape, or sports shots by knowing the equivalent reach ahead of time.
Quickly verify the 35mm equivalent when reading a camera spec sheet.
Evaluate whether a wide-angle lens is still wide enough on a crop sensor.

Frequently Asked Questions

Last updated: 2026-06-11 · Reviewed by Nham Vu