Magnification Calculator
Find the total magnification of a microscope or telescope. A microscope multiplies the objective and eyepiece powers; a telescope divides the objective focal length by the eyepiece focal length.
How to find total magnification
- Choose microscope or telescope.
- For a microscope, enter the objective and eyepiece magnifications.
- For a telescope, enter the objective and eyepiece focal lengths in the same unit.
Examples
Microscope
40x objective, 10x eyepiece
total magnification = 400x
Telescope
objective focal length = 1000 mm, eyepiece focal length = 25 mm
magnification = 40x
Frequently asked questions
How do you calculate microscope magnification?
Multiply the objective magnification by the eyepiece magnification. A 40x objective with a 10x eyepiece gives 400x total.
How do you calculate telescope magnification?
Divide the objective (or main mirror) focal length by the eyepiece focal length. A 1000 mm objective with a 25 mm eyepiece gives 40x.
Do the telescope focal lengths need the same units?
Yes. Because magnification is a ratio, both focal lengths must be in the same unit, such as millimeters, and the result is unitless.
What does the x mean in magnification?
The x means times. A magnification of 400x means the image looks 400 times larger in linear size than the object seen with the naked eye.
Why must the values be positive?
Objective and eyepiece magnifications and focal lengths are physical sizes greater than zero, so zero or negative inputs are rejected.
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