Magnification Calculator

Magnification is the number that tells you how much bigger, or smaller, an image is than the object that produced it, and this calculator finds it two ways depending on what you have measured. Choose the heights method, enter the object height and the image height, and it gives the magnification straight from their ratio. Or choose the distances method, enter how far the object and image sit from a lens or mirror, and it works out the magnification from the geometry of the optics. Either way the result, the magnification factor, appears as you type, along with whether the image is upright or inverted and whether it is enlarged or reduced. The idea is simple but rich. A magnification of three means the image is three times the size of the object, a magnification of one half means it is shrunk to half, and a magnification of one means the image is the same size. The sign carries extra meaning: a negative value, which arises naturally from the lens and mirror formula, tells you the image is flipped upside down, while a positive value means it stays the right way up. The distances version, magnification equals minus the image distance over the object distance, is the one that links directly to the thin lens and mirror equations, so it slots neatly into a full optics problem. That makes the tool genuinely useful for physics students learning about lenses, mirrors, cameras, microscopes and telescopes and checking homework, and for anyone working out image sizes in optical setups, photography or projection. Use any consistent length units for the heights or distances, since magnification is a pure ratio with no units of its own. The formulas and a worked example are explained clearly below.

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