Magnification Calculator

About this calculator

Lens magnification is m = −dᵢ / dₒ (image distance divided by object distance, with the sign convention indicating whether the image is upright or inverted), which equals the ratio of image height to object height, m = hᵢ / hₒ. This calculator derives both the magnification factor and the resulting image height directly from the object and image distances, following from the thin-lens equation.

Optics students use magnification to connect lens theory to observable image behavior, and it's core to designing real optical instruments — telescopes and microscopes combine multiple lenses' magnifications multiplicatively, camera lenses use it to determine how large a subject appears on the sensor, and optometrists reference related magnification concepts when discussing corrective lens power. Enter the object and image distances (and object height, if known) to get magnification and image size.