Thin Lens Equation Calculator
Image distance and magnification for a lens or mirror.
Enter your values
ⓘ Live results
Results
- Image distance
- 15 cm
- Magnification
- -0.5
- Image type
- Real, inverted
Quick answer
1/f = 1/do + 1/di, magnification = -di/do.
1/f = 1/do + 1/di
How to use the Thin Lens Equation Calculator
- 1Enter the focal length (positive for converging, negative for diverging lenses).
- 2Enter the object distance from the lens.
- 3Read the image distance and magnification.
Worked example
Using the values the calculator loads with:
Inputs
- Focal length10 cm
- Object distance30 cm
Results
- Image distance15 cm
- Magnification-0.5
- Image typeReal, inverted
Frequently asked questions
What does negative magnification mean?
The image is inverted relative to the object, common for real images from converging lenses.
Does this work for mirrors too?
Yes, the same equation applies to spherical mirrors using the same sign convention.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.