Thin Lens Equation Calculator
Image distance and magnification for a lens or mirror.
Reviewed by the Calculation Machine team · How we check our maths
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.
The formula
1/f = 1/do + 1/di
Worked example
Worked example
Using the values the calculator loads with.
Inputs
- Focal length10 cm
- Object distance30 cm
Result
- Image distance15 cm
- Magnification-0.5
- Image typeReal, inverted
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.
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 the Calculation Machine team · How we build and test calculators
- Report an error