About the Stellar Magnitude Calculator
Convert between apparent magnitude, absolute magnitude, and distance, and compare star brightness directly.
What it is
A star's apparent brightness depends on both how luminous it truly is and how far away it is. Absolute magnitude strips out the distance factor, letting astronomers compare stars on equal footing. This tool implements the distance modulus relation M = m โ 5logโโ(d) + 5, solving for whichever of the three quantities you don't already know.
Features
Solve for m, M, or distance
Enter any two values and the calculator finds the third, with the substituted formula shown.
Parsec / light-year toggle
Enter or read distance in whichever unit you prefer.
Brightness-ratio tool
Compare two magnitudes directly using the Pogson relation to see exactly how many times brighter one star is.
Real star presets
Load the Sun, Sirius, Betelgeuse, or Polaris to see the formula applied to known values.