Habitable Zone Distance Calculator

About this calculator

The circumstellar habitable zone — nicknamed the “Goldilocks zone” — is the range of orbital distances from a star where a rocky planet with the right atmosphere could sustain liquid water on its surface, neither boiling away nor permanently frozen. It's typically estimated by scaling the solar system's boundaries (roughly 0.95–1.4 AU for the Sun) by the square root of the star's luminosity relative to the Sun's, since a planet's equilibrium temperature depends on the flux it receives, which falls off with distance squared.

Astronomers and astrobiologists apply this calculation to newly discovered exoplanets — including systems found by missions like Kepler and TESS — as a first-pass filter for identifying worlds worth investigating further for potential habitability, before more detailed climate modeling accounts for atmospheric greenhouse effects, cloud cover, and orbital eccentricity.

This calculator estimates the inner and outer habitable zone boundaries from a star's luminosity, or from its radius and effective temperature if luminosity isn't known directly — handy for astronomy students, exoplanet enthusiasts, and science communicators exploring “could life exist there” questions.