Lens and Mirror Equation

Solve focal length, object distance, image distance, magnification, and image height using 1/f = 1/do + 1/di. Free online calculator with formulas and step-by-step solutions.

About this tool

Solve focal length, object distance, image distance, magnification, and image height using 1/f = 1/do + 1/di. Free online calculator with formulas and step-by-step solutions.

How to use this calculator

1. Choose the variable you want to solve for and confirm which values are already known.
2. Enter inputs in consistent units before calculating so the formula is applied correctly.
3. Check whether the result is physically reasonable by comparing it with the size of the inputs.
4. Use the step-by-step breakdown to see how the equation was rearranged and evaluated.