Absolute Magnitude Calculator

About this calculator

This calculator uses the distance modulus formula, M = m − 5·log₁₀(d/10), to convert a star's apparent magnitude m (how bright it looks from Earth) into its absolute magnitude M — the magnitude it would have if viewed from a standard distance of 10 parsecs. Because the magnitude scale is logarithmic and inverted (lower numbers mean brighter objects), this lets astronomers strip out the effect of distance and compare stars' true, intrinsic luminosities directly.

Astronomers and astrophysics students use absolute magnitude to build the Hertzsprung-Russell diagram, classify stars by luminosity class, and calibrate standard candles like Cepheid variables and Type Ia supernovae used to measure cosmic distances. Enter the apparent magnitude and distance in parsecs to get the absolute magnitude.