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Calcimator

Stellar Physics Calculator

Complete stellar physics calculations. Analyze luminosity, temperature, nuclear fusion, stellar evolution, black body radiation, and stellar distances.

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Step 1 of 2

How to Use This Calculator
  1. Enter Surface Temperature (K) and Radius (solar radii) to compute luminosity via the Stefan-Boltzmann law.
  2. Enter Initial Mass (solar masses), Current Age (Gyr), and Metallicity to trace the star's evolutionary stage.
  3. For distance estimation, enter Apparent Magnitude and Absolute Magnitude or Parallax (arcsec) to compute Distance (pc).
  4. Read the Stellar Comparison chart to see where the star falls relative to the Sun, Sirius, Betelgeuse, and Proxima Centauri on an H-R diagram.
  5. Use pp-chain and CNO cycle dominance outputs to understand which nuclear fusion pathway dominates at the star's core temperature.

How the result changes with Surface Temperature (K)

Surface Temperature (K)Luminosity (L☉)Absolute Magnitude
2,3110.038.81
8,0893.863.36
15,02345.890.68
20,801168.67-0.74

What each input means

Calculation Type
Calculation mode to use.
Stellar Mass (M☉)
Mass in solar masses
Stellar Radius (R☉)
Radius in solar radii
Surface Temperature (K)
Effective surface temperature
Core Temperature (Million K)
Sun's core is 15.7 MK
Hydrogen Mass Fraction
Typical: 0.71 for solar composition
Helium Mass Fraction
Typical: 0.27 for solar composition
Current Age (Billion Years)
Sun is 4.6 billion years old
Metallicity (Z/Z☉)
1 = Solar, <1 = metal-poor, >1 = metal-rich
Temperature (K)
Temperature in the selected unit.
Radius (R☉)
Distance from center to edge.
Apparent Magnitude (m)
How bright star appears from Earth
Absolute Magnitude (M)
Brightness at 10 parsecs (Sun = 4.83)
Parallax (arcseconds)
Annual parallax shift (optional)
Distance (parsecs)
Known distance (optional)

How this is calculated

Formula

L = 4πR²σT⁴ (Stefan-Boltzmann) | λ_peak = b/T (Wien's Law) | m - M = 5log₁₀(d) - 5

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Calculation Type = 0, Stellar Mass (M☉) = 1, Stellar Radius (R☉) = 1, Surface Temperature (K) = 5778 = 17 input(s) provided
  2. Calculate Luminosity
    Luminosity
    1.0041621057332157 = 1.0041621057332157
  3. Calculate Absolute Magnitude
    4.825490429276023 = 4.825490429276023
  4. Calculate Peak Wavelength
    Peak Wavelength
    501.51816458982347 = 501.51816458982347
  5. Calculate Spectral Class
    Spectral Class
    G = G

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