Telescope Magnification Calculator
Result
Calculated result
100
Based on the values entered.
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Calculate telescope magnification from telescope and eyepiece focal lengths.
Formula
Magnification = Telescope focal length ÷ Eyepiece focal length
- Magnification is the telescope focal length divided by the eyepiece focal length.
- The main inputs are Telescope focal length, Eyepiece focal length. Enter them in the units and format shown in the calculator.
- Use the units, labels and assumptions shown beside each input so the formula is applied consistently.
- Changing any input above recalculates the result with the same calculation engine used by this page.
Example: Telescope Magnification
Inputs
- Telescope focal length: 1000 mm
- Eyepiece focal length: 10 mm
A 1,000 mm telescope with a 10 mm eyepiece gives 100× magnification.
Sample result: Calculating…
Frequently asked questions
What does this calculator estimate?
It calculates nominal optical magnification.
Is this an exact mission-planning tool?
No. It is an educational calculator based on the stated constants and simplified assumptions.
How accurate is the result?
Actual useful magnification also depends on aperture, seeing, optics and target brightness.
What does the Telescope Magnification calculate?
Calculate telescope magnification from telescope and eyepiece focal lengths.
Which values should I enter?
Enter Telescope focal length, Eyepiece focal length using the units and format shown beside each field.
What formula does this calculator use?
The calculator uses the following relationship: Magnification = Telescope focal length ÷ Eyepiece focal length.