Mirror Equation Calculator
Calculate image distance, magnification, and image characteristics for concave and convex mirrors using the mirror equation 1/s + 1/s' = 1/f.
Spherical mirrors obey the paraxial mirror equation 1/s + 1/s′ = 1/f, where object distance s and image distance s′ are measured from the mirror vertex and f = R/2 is the focal length. For concave mirrors f is positive and real images form in front of the mirror; for convex mirrors f is negative and only virtual images form behind the mirror. This calculator accepts either radius of curvature R or focal length f directly, applies sign conventions automatically based on mirror type, and computes image distance, lateral magnification m = −s′/s, image height from object height, and image characteristics — real or virtual, upright or inverted, magnified or diminished. Use it to locate the image plane when designing a reflective telescope, retroreflector, or collection optic, or to check whether a concave mirror produces a real or virtual focus for a given object position.