Mirror Equation Calculator
Calculate image position and magnification for concave and convex mirrors.
Results
The mirror equation has the same form as the thin lens equation: 1/f = 1/do + 1/di. For concave mirrors (positive f), objects beyond the center of curvature produce real, inverted images. For convex mirrors (negative f), images are always virtual, upright and diminished. This calculator handles both mirror types and determines image characteristics.
Explore all our optics calculator tools, or browse the full cooking hub.
Frequently asked questions
1/di = 1/15 - 1/30 = 1/30, so di = 30 cm. The image is real, inverted and 1.0× (same size). This is the center of curvature (2f = 30 cm).
Always virtual, upright and reduced. With f = -15 cm and do = 30 cm: di = -10 cm, M = +0.333×. The image appears behind the mirror at 1/3 the size. Car side mirrors use this for wide field of view.
When the object is between f and 2f. With f = 15 cm and do = 20 cm: di = 60 cm, M = -3×. The image is real, inverted and 3 times larger. Makeup mirrors use this principle.
Light reflects as parallel rays - no image forms (di = ∞). This is how flashlights and car headlights work: the bulb sits at the focal point to produce a parallel beam.
Focal length is half the radius of curvature: f = R/2. A mirror with 30 cm radius has f = 15 cm. You can measure f by finding where a distant object (sun) focuses to a point.