Stellar Lifetime Calculator

A star's main-sequence lifetime is the time it spends fusing hydrogen in its core. It depends strongly on mass: more massive stars burn far hotter and exhaust their fuel much faster. The Sun's main-sequence lifetime is about 10 billion years, and other stars scale from that benchmark by their mass and luminosity.

It uses lifetime = t_sun * (M / M_sun) / (L / L_sun), the fuel divided by the burn rate, where luminosity follows the mass-luminosity relation L/L_sun = (M/M_sun)^a. With the common exponent a = 3.5, this simplifies to lifetime = t_sun * (M/M_sun)^(1 - 3.5) = t_sun * (M/M_sun)^(-2.5). The solar lifetime and exponent are user-editable.

Although a massive star has more hydrogen fuel, its luminosity rises far faster than its mass (roughly as mass to the 3.5 power). The fuel grows linearly with mass but the consumption rate grows much faster, so the net lifetime falls sharply. A 10 solar mass star lives only a few tens of millions of years.

The exponent in L proportional to M to the power a varies with stellar mass, but a value near 3.5 is a widely used average for main-sequence stars of roughly solar mass. This calculator exposes the exponent as a user-editable input so you can apply 3.0, 3.5, 4.0, or a piecewise value as your reference requires.

No. It is a scaling estimate calibrated to the Sun, not a detailed stellar evolution model. Real lifetimes depend on metallicity, rotation, mass loss, and the exact mass-luminosity behavior across the mass range. Treat the result as an order-of-magnitude main-sequence lifetime, useful for comparison and teaching.