Magnification Calculator
Enter object and image distances to compute the linear magnification m = −d_i/d_o of a lens or mirror.
Input Data
Results
At a glance:Linear magnification m is the ratio of image height to object height, equal to m = h_i/h_o = −d_i/d_o, where d_o is the object distance and d_i the image distance (using the sign convention of the lens/mirror equation). A positive m means upright (virtual) image; negative m means inverted (real) image. |m|>1 means enlarged, |m|<1 reduced. It combines with the lens/mirror equation 1/f = 1/d_o + 1/d_i. This tool returns m from d_i and d_o.
Formula
Magnification: m = −d_i/d_o = h_i/h_o
$$m = -\dfrac{d_i}{d_o}$$How to Use
- Enter the image distance d_i.
- Enter the object distance d_o.
- The calculator returns the magnification m.
Case Studies
Projector lens
d_o = 0.2 m, d_i = 2 m.
m = −2/0.2 = −10.
Image is 10× larger and inverted.
FAQ
What does a negative magnification mean?
The image is inverted relative to the object — typical of real images formed by convex lenses and concave mirrors.
How is magnification related to image size?
Image height h_i = m·h_o; |m| tells how many times larger or smaller the image is than the object.
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References
Content review: Calculatorism Science Team. Results are for reference only; please refer to the relevant authorities for the official figures.