Stellar Mass Calculator

Mass-from-luminosity (M = L^(1/3.5)) and mass-from-radius (M = R^(1/0.8)) are both empirical approximations, each with its own weaknesses depending on the star's evolutionary stage. Averaging them gives a rough consistency check rather than a rigorous joint fit — if the two disagree substantially, that itself is informative, since it usually signals the star isn't a well-behaved main-sequence object where these simple power laws apply cleanly.

Mass-from-orbit is the only method here based on rigorous physics rather than an approximate power law: it applies Kepler's Third Law directly, the same 4π²a³/(GT²) relation used to find orbital periods, but solved in reverse for mass. This only works for binary systems where you can observe both the orbital period and separation, which is in fact how astronomers determine stellar masses with real confidence in practice.

It's the combined mass of both stars in the binary system, not either star individually — Kepler's Third Law as applied here solves for the total system mass that produces the observed orbital period at the given separation. Splitting that combined mass between the two individual stars requires additional information, such as their mass ratio from radial velocity data, which this calculator doesn't take as input.

The lifetime estimate scales as M⁻²·⁵, a simplified relation that's most trustworthy near solar mass. It's built on the same estimated mass from the luminosity/radius average, so if that estimate is already shaky for a very massive O-type star or a tiny dwarf — where the underlying mass-luminosity and mass-radius power laws are less accurate — the lifetime figure inherits and compounds that uncertainty.