About the Lens Equation Calculator

A free tool for solving the thin lens equation and interpreting the resulting image.

What it is

This calculator solves 1/f = 1/dโ‚’ + 1/dแตข for focal length, object distance, or image distance โ€” whichever you leave blank โ€” and also reports magnification, whether the image is real or virtual, and whether it's upright or inverted.

Features

Solve for any variable

Leave f, dโ‚’, or dแตข blank and the calculator finds it.

Magnification

See the image size ratio and orientation.

Image type

Real or virtual, upright or inverted, determined automatically.

Instant, private

Runs entirely in your browser. No data is sent anywhere.

Ready to use it?

Free, no sign-up required.

Open the Lens Equation Calculator