Magnification on a telescope is set by the eyepiece, not the tube, so the same scope can run at many different powers. This calculator divides the telescope focal length by the eyepiece focal length to give the magnification for any eyepiece you own, and it also estimates the maximum useful magnification from your aperture, roughly fifty times the aperture in inches or two times the aperture in millimeters. Push past that limit and the image just gets dim and mushy instead of showing more detail. Enter the numbers below to plan an eyepiece kit that covers low power for star fields and high power for planets, all computed locally in your browser with nothing sent to a server.
Magnification on a telescope is set by the eyepiece, not the tube, so the same scope can run at many different powers. This calculator divides the telescope focal length by the eyepiece focal length to give the magnification for any eyepiece you own, and it also estimates the maximum useful magnification from your aperture, roughly fifty times the aperture in inches or two times the aperture in millimeters.
Yes. Telescope Magnification Calculator is completely free, with no sign-up and no usage limits.
Yes. Telescope Magnification Calculator runs in any modern web browser. There is nothing to download or install.
Yes. Telescope Magnification Calculator runs entirely on your device in your browser, so nothing you enter is uploaded to a server.