Magnification of a Lens

About this calculator

For a thin lens, magnification is m = −v/u, where v is the image distance and u the object distance (using the standard sign convention where distances measured on the outgoing side of the lens are positive). The magnitude of m tells you the size ratio between image and object, while its sign tells you the orientation: negative means inverted, positive means upright.

Optics students use it to predict whether a lens produces a magnified or reduced, real or virtual image before ever setting up an experiment, and camera, telescope, and microscope designers use the same relationship to work out how a chosen lens-to-sensor or lens-to-eyepiece distance will actually magnify the final image.