Astronomical Tools

These interactive tools are designed for amateur astronomers and telescope enthusiasts. By inputting your telescope and eyepiece specifications, you can calculate essential astronomical values such as focal length, magnification, field of view, and resolution limits. Whether you're planning your next stargazing session or trying to get the most out of your equipment, our Astronomy Calculators are an invaluable resource.


In the realm of stargazing, magnification is a cornerstone of observation. It refers to the extent to which an image or object is enlarged. A telescope's magnification is determined by the ratio of its focal length to the eyepiece's focal length.

Focal Length

Focal length is another integral parameter in astronomy. It is the distance from a lens (or mirror in the case of reflector telescopes) to the point where it converges light rays to form a sharp image.

Focal Ratio

The focal ratio (or f-number) of a telescope is the ratio of its focal length to its aperture. It is calculated using the formula

True Field of View

The True Field of View Calculator is an essential tool for astronomy enthusiasts and professionals. It allows you to calculate the true field of view (TFOV) that you'll observe when looking through a telescope with a specific eyepiece.

Resolving Power

A calculator for Dawes limit and Rayleigh's limit is a tool designed to assist astronomers and stargazers in determining the resolving power or angular resolution of an optical instrument, such as a telescope. Resolving power refers to the ability of an instrument to distinguish two closely spaced objects as separate entities.