About Camera Math Calculators

Last updated June 5, 2026

I shoot with both a full-frame body and a Micro Four Thirds kit, and got tired of re-deriving depth of field, equivalent focal length, and the 500 rule in my head out in the field. These are the camera and lens calculators I actually use — every one shows the optics so you can check it instead of trusting it.

What’s on this site

Right now there are 6 calculators here: Depth of Field Calculator, Field of View Calculator, Crop Factor Calculator, Hyperfocal Distance Calculator, Exposure Value (EV) Calculator, and Night Sky 500 Rule Calculator. Each one is a single-purpose tool that shows its formula, lists its assumptions, and runs on any device with no signup.

Why these are different

A lot of calculators are black boxes — you get a number and no way to tell if it’s right. These work the other way around: the formula, the constants, and a worked example sit on the page next to the result, so you can redo the math by hand. No account, no paywall, no signup.

How the math is kept honest

Each formula is shown in full and was independently re-derived and spot-checked against the calculator’s code. Reference values (typical rates, averages, rules of thumb) are labeled as approximate and are editable, so you can put in your own real numbers. These are optical estimates and rules of thumb, not a guarantee of sharpness — circle of confusion, the 500 rule, and equivalence are simplifications, so trust your own test shots for critical work.

Found a mistake?

I’d genuinely like to know. Email [email protected] and I’ll fix it.