Bokeh Calculator

Summary

Enter focal length, aperture, subject distance, and sensor size to calculate background blur diameter and depth of field for beautiful bokeh.

How it works

1. Select your sensor format — or enter a custom circle of confusion (CoC).
2. Enter the focal length of your lens in millimeters.
3. Enter the aperture as an f-number (e.g. 1.4, 2.8, 5.6).
4. Enter the distance from your camera to the subject.
5. Enter the distance to the background object you want blurred.
6. Read the blur disc diameter, depth of field, and blur ratio in the results panel.

Use cases

• Choose the right lens and aperture to achieve creamy background separation for portraits.
• Compare how full-frame vs. APS-C vs. Micro Four Thirds affects bokeh at the same framing.
• Determine the minimum aperture to blur a distracting background element.
• Plan macro shots by understanding how thin the in-focus zone is at close distances.
• Evaluate whether a background at a given distance will be pleasingly blurred or still recognizable.
• Teach photography students the relationship between aperture, focal length, and background blur.
• Compare two lens options (e.g. 85 mm f/1.8 vs. 135 mm f/2) for subject isolation.

Frequently Asked Questions