How to use the mirror equation calculator
Find the image position for a concave or convex mirror. Enter focal length (concave +), object distance in the fields above; the image distance, magnification are computed instantly and plotted on the chart so you can see how the answer changes.
Formula
Variables
- f — Focal length (concave +) (cm)
- dobj — Object distance (cm)
Worked example
With focal length (concave +) = 15 cm, object distance = 40 cm, the calculator gives image distance ≈ 24 cm; magnification ≈ -0.6.
Frequently asked questions
What is the formula for the mirror equation calculation?
Image distance (cm) = 1 / (1 / f-1 / dobj). Magnification = -[Image distance] / dobj. Here f is focal length (concave +) (cm), dobj is object distance (cm).
What inputs do I need for the mirror equation calculator?
You need focal length (concave +) in cm, object distance in cm. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use this calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.