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Circle of Confusion Calculator

Compute the acceptable circle of confusion used in DOF calculations.

Introduction

Circle of Confusion Calculator — Compute the acceptable circle of confusion used in DOF calculations. Enter Sensor Width, Sensor Height, CoC Divisor Standard to get an instant, accurate result.

Formula

CoC = sensor diagonal / divisor, where sensor diagonal = √(width² + height²) and the divisor is a standard constant (commonly 1500 or 1442, depending on the acceptable-sharpness criterion chosen).

Step-by-step

  1. Enter the Sensor Width.
  2. Enter the Sensor Height.
  3. Enter the CoC Divisor Standard.
  4. Click Calculate to see your result instantly.

Real-world example

Example: With Sensor Width = 36 mm, Sensor Height = 24 mm, CoC Divisor Standard = 1500, the Circle of Confusion Calculator gives Sensor Diagonal Mm: 43.2666, Coc Mm: 0.0288.

Frequently Asked Questions

Why is the divisor adjustable?
Different references use different divisors (e.g. 1500, 1442, 1730) depending on assumed print size, viewing distance, and visual acuity — 1500 is a common general-purpose default.
Why do smaller sensors have a smaller circle of confusion?
CoC scales with sensor diagonal, so a smaller sensor produces a smaller acceptable blur circle, which is why smaller-sensor cameras need tighter apertures to achieve the same relative depth of field.
What inputs does the Circle of Confusion Calculator need?
You'll need to provide: Sensor Width, Sensor Height, CoC Divisor Standard. All fields use sensible defaults, so you can see a working example immediately and then adjust the values to match your own numbers.
How accurate is the Circle of Confusion Calculator?
The Circle of Confusion Calculator applies the formula exactly as calculated — CoC = sensor diagonal / divisor, where sensor diagonal = √(width² + height²) and the divisor is a standard constant (commonly 1500 or 1442, depending on the acceptable-sharpness criterion chosen). — so results are precise for the inputs you provide. Accuracy depends on entering correct, realistic input values.
Is the Circle of Confusion Calculator free to use?
Yes, the Circle of Confusion Calculator is completely free, requires no signup, and runs instantly in your browser.

About the Circle of Confusion Calculator

The Circle of Confusion Calculator uses a real, verifiable formula — CoC = sensor diagonal / divisor, where sensor diagonal = √(width² + height²) and the divisor is a standard constant (commonly 1500 or 1442, depending on the acceptable-sharpness criterion chosen). — so results are accurate every time, not an approximation.