Stellar Lifetime Calculator
Estimate how long a star will burn hydrogen on the main sequence from its mass relative to the Sun.
solar masses
solar luminosities
10,000,000,000 years
- 1
Luminosity (L ≈ M^3.5)
1^3.5 = 1 L☉ - 2
Lifetime in years: t☉ × M ÷ L
10¹⁰ × 1 ÷ 1 = 10,000,000,000t☉ = 10¹⁰ yr is the calibration lifetime of the Sun. - 3
Lifetime in Gyr (÷ 10⁹)
10,000,000,000 ÷ 10⁹ = 10
How does this calculator work?
A star's main-sequence lifetime is its fuel divided by its burn rate: t = t☉ × (M/M☉)/(L/L☉). Using L ≈ M^3.5 gives t ≈ 10 Gyr × (M/M☉)^−2.5. A Sun-mass star lasts about 10 billion years, while massive stars burn out in millions of years and tiny red dwarfs endure for trillions.
Formula
How this is calculated
A star's main-sequence lifetime is set by how much fuel it has (its mass) divided by how fast it burns that fuel (its luminosity). Using the Sun as a calibration point with t☉ ≈ 10 billion years, the lifetime is t = t☉ × (M/M☉) / (L/L☉). Enter the stellar mass M in solar masses; you may optionally enter the luminosity L in solar luminosities.
If luminosity is left blank, it is estimated from the mass-luminosity relation L ≈ M^3.5, which holds reasonably well for main-sequence stars. Substituting this gives the compact form t ≈ 10 Gyr × (M/M☉)^−2.5: doubling a star's mass cuts its life to roughly one-sixth. This is why massive O and B stars live only a few million years while red dwarfs persist for trillions of years.
The model assumes a main-sequence star fusing hydrogen in its core and a fixed fraction of mass available as fuel. It is an order-of-magnitude estimate: the exponent in the mass-luminosity relation actually varies (closer to 4 for mid-range stars and ~2.3 for very massive ones), and post-main-sequence phases are not included. Mass must be positive; results are reported in years and gigayears (Gyr).
Frequently asked questions
Although heavy stars have more fuel, their luminosity rises far faster than their mass (roughly L ∝ M^3.5), so they consume fuel disproportionately quickly and exhaust their core hydrogen much sooner.
For M = 1 solar mass (and the default L ≈ 1), the calculator returns about 10 Gyr, matching the commonly cited ~10-billion-year main-sequence lifetime of the Sun.
Yes. Supplying a measured luminosity overrides the L ≈ M^3.5 estimate and gives a more accurate lifetime, since real stars deviate from the simple mass-luminosity power law.
Also known as
TG we-Calculate Editorial Team. (2026). Stellar Lifetime Calculator [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/stellar-lifetime-calculator
TG we-Calculate Editorial Team. "Stellar Lifetime Calculator." TG we-Calculate. 2026. https://we-calculate.com/calculator/stellar-lifetime-calculator.
TG we-Calculate Editorial Team, "Stellar Lifetime Calculator," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/stellar-lifetime-calculator
@misc{wecalculate_stellar_lifetime_calculator, title = {Stellar Lifetime Calculator}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/stellar-lifetime-calculator}}, year = {2026}, note = {TG we-Calculate} }
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