Magnification Calculator Formula
Understand the math behind the magnification calculator. Each variable explained with a worked example.
Formulas Used
Magnification
magnification = -(image_distance) / object_distance|Magnification|
abs_magnification = abs(image_distance / object_distance)Variables
| Variable | Description | Default |
|---|---|---|
image_distance | Image Distance(cm) | 15 |
object_distance | Object 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.
Worked Example
Image at 15 cm, object at 30 cm.
- 01M = -di / do
- 02M = -15 / 30
- 03M = -0.5
- 04The image is inverted and half the size of the object.
Frequently Asked Questions
What does negative magnification mean?
The image is inverted (flipped upside down) relative to the object. Positive magnification means an upright image.
What magnification does a flat mirror give?
M = +1, meaning the image is the same size and upright, but laterally reversed (left-right swap).
How does a microscope achieve high magnification?
By combining an objective lens (high magnification) with an eyepiece lens (additional magnification). Total magnification is the product of both.
Learn More
Guide
Understanding Optics and Lenses
A complete guide to optics and lenses. Learn about refraction, Snell's law, converging and diverging lenses, the thin lens equation, magnification, mirrors, and optical instruments.
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Open Magnification Calculator