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Lens Formula Calculator

Thin lens equation (1/f = 1/v − 1/u): solve for focal length, object or image distance, with magnification.

Also known as thin lens equation, image distance calculator, object distance.

Enter values

Results update as you type.

Result

Image distance

15 cm

Magnification
-0.5 ×
Image type
Real and inverted
Size
Reduced

About the Lens Formula Calculator

Thin lens equation (1/f = 1/v − 1/u): solve for focal length, object or image distance, with magnification.

Also known as: thin lens equation, image distance calculator, object distance, lens equation, image-distance, object-distance.

How to use this calculator

  1. Enter solve for.
  2. The result updates instantly as you type — press Calculate (or Enter) at any time.
  3. Review the breakdown shown under the main result.
  4. Use Copy result or Share to save the answer or send a link with your inputs.

Lens Formula formula

1/f = 1/v + 1/u · m = −v/u

Worked example

Using the values pre-filled in the calculator above:

  • Solve for: Image distance
  • Focal length = 10 cm
  • Object distance = 30 cm

the calculator returns:

  • Image distance: 15 cm
  • Magnification: -0.5 ×
  • Image type: Real and inverted
  • Size: Reduced