Thin Lens Equation Calculator
Solve the thin lens equation 1/f = 1/do + 1/di.
Enter any two of focal length, object distance, or image distance to find the third.
Lens Equation Result
Thin Lens Equation:
1/f = 1/do + 1/di
Where:
- f = focal length (positive for converging lens, negative for diverging)
- do = object distance (distance from object to lens, always positive for real objects)
- di = image distance (positive = real image on opposite side, negative = virtual image on same side)
Rearranged forms:
f = (do × di) / (do + di)do = (f × di) / (di − f)di = (f × do) / (do − f)
Magnification: M = −di / do
- |M| > 1: image is enlarged
- |M| < 1: image is reduced
- M > 0: image is upright (virtual)
- M < 0: image is inverted (real)
Leave one field blank to solve for it.