Mirror Equation Calculator

Your details

Choose the unknown. Enter the other two values and the calculator solves the mirror equation for it.
Sets the sign of the focal length. Concave and converging are positive; convex and diverging are negative.
All distances share this unit. Switch freely between metric and imperial.
Magnitude of the focal length. The type selector above sets its sign. Focal length is half the radius of curvature.
cm
How far the object sits in front of the mirror. Use a positive value for a real object.
cm
Enter a height to also get the image height. Leave at 0 to skip it.
cm
Solved valueReal image (inverted)
15cm
Linear magnification (m)-0.5
Areal magnification (m²)0.25
Radius of curvature (R = 2f)20cm
-0.5 x
Inverted, enlarged<-1Inverted, reduced-1-0Upright, reduced0-1Upright, enlarged1+

Image distance = 15 cm, magnification -0.5x.

  • The image distance works out to 15 cm.
  • The image is real: light actually converges there and it can be projected onto a screen.
  • Linear magnification is -0.5, so the image is inverted (upside down) and reduced (|m| = 0.5); the area scales by 0.25.

Next stepThe radius of curvature is twice the focal length, useful when grinding or specifying a mirror.

 = Powered by OnlyCalculators