Magnification Calculator Formula

Understand the math behind the magnification calculator. Each variable explained with a worked example.

Use the Magnification Calculator

Formulas Used

Magnification

magnification = -(image_distance) / object_distance

|Magnification|

abs_magnification = abs(image_distance / object_distance)

Variables

VariableDescriptionDefault
image_distanceImage Distance(cm)15
object_distanceObject Distance(cm)30

How It Works

Optical Magnification

Magnification describes the ratio of image size to object size.

Formula

M = -d_i / d_o = h_i / h_o

Negative M means the image is inverted. |M| > 1 means the image is enlarged; |M| < 1 means it is reduced.

Worked Example

Image at 15 cm, object at 30 cm.

image_distance = 15object_distance = 30
  1. 01M = -di / do
  2. 02M = -15 / 30
  3. 03M = -0.5
  4. 04The image is inverted and half the size of the object.

Ready to run the numbers?

Open Magnification Calculator