Absolute Magnitude Calculator Formula

Understand the math behind the absolute magnitude calculator. Each variable explained with a worked example.

Use the Absolute Magnitude Calculator

Formulas Used

Absolute Magnitude

abs_magnitude = app_magnitude - 5 * log10(distance_pc / 10)

Variables

VariableDescriptionDefault
app_magnitudeApparent Magnitude (m)-1.46
distance_pcDistance(pc)2.64

How It Works

Absolute Magnitude

Absolute magnitude (M) is the apparent magnitude a star would have at a standard distance of 10 parsecs.

Formula

M = m - 5 log10(d / 10)

This removes the effect of distance, allowing direct comparison of intrinsic brightnesses.

Worked Example

Sirius: m = -1.46 at d = 2.64 pc.

app_magnitude = -1.46distance_pc = 2.64
  1. 01M = m - 5 log10(d/10)
  2. 02log10(2.64/10) = log10(0.264) = -0.578
  3. 03M = -1.46 - 5 × (-0.578) = -1.46 + 2.89 = 1.43
  4. 04Sirius has absolute magnitude ≈1.43.

Ready to run the numbers?

Open Absolute Magnitude Calculator