Main Sequence Star Lifetime Calculator
A star's main sequence lifetime is set by how much hydrogen fuel it has and how quickly it burns it. Fuel scales with mass, but luminosity scales much more steeply with mass, so heavier stars burn out faster despite starting with more fuel. Using the Sun as a reference and a mass-luminosity exponent, you can estimate the main sequence lifetime of any star from its mass alone. This calculator returns the lifetime in years and in solar lifetimes, plus the star's estimated luminosity relative to the Sun. The reference lifetime and exponent are user-editable so you can match your chosen model.
Star lifetime formula
L / Lsun = M^a (a = mass-luminosity exponent)
t / tsun = M / (L / Lsun) = M^(1 - a)
lifetime = tsun * M^(1 - a)
with a = 3.5: t / tsun = M^(-2.5)
Mass and luminosity are in solar units. The lifetime is the fuel (mass) divided by the burn rate (luminosity), scaled to the Sun's main sequence lifetime.
Stellar lifetime notes
- This is an order-of-magnitude estimate, not a detailed stellar-evolution model.
- Massive stars are short-lived; a 10-solar-mass star lasts only tens of millions of years.
- Low-mass red dwarfs can last far longer than the current age of the universe.
- The exponent is steeper near solar masses and shallower for very massive stars.
- It covers the hydrogen-burning main sequence phase only.
Star lifetime: frequently asked questions
How is main sequence lifetime estimated from mass?
A star's lifetime scales as its fuel divided by its burn rate. Fuel scales with mass, and luminosity scales steeply with mass (roughly mass to the 3.5 power for many main sequence stars). Combining these, lifetime scales as mass divided by luminosity, or about mass to the power of minus 2.5, relative to the Sun's roughly 10-billion-year main sequence lifetime.
What reference lifetime does this use?
It uses the Sun's main sequence lifetime, commonly taken as about 10 billion years, as the reference, and a user-editable mass-luminosity exponent (default 3.5). Both the reference lifetime and the exponent are inputs so you can match the model you prefer.
Why do massive stars live shorter lives?
Massive stars are vastly more luminous than low-mass stars. Although they start with more hydrogen fuel, they burn it so much faster that their net lifetime is far shorter. A star ten times the Sun's mass lives only a few tens of millions of years rather than billions.
Is the mass-luminosity exponent always 3.5?
No. The exponent varies across the main sequence: it is steeper near solar masses and shallower for very massive stars. The exponent is user-editable so you can use 3.0, 3.5, or 4.0 as appropriate for the mass range you are studying. This is an order-of-magnitude estimate.
What is the main sequence?
The main sequence is the long, stable phase of a star's life during which it fuses hydrogen into helium in its core. Most stars, including the Sun, spend the majority of their existence here. This calculator estimates the duration of that phase only.
Official sources
- NASA Imagine the Universe: stellar evolution and the main sequence.
- NASA Science: the life cycles of stars.
Reviewed by the CalculatorHub team, edited by James Graham, 17 June 2026. See our methodology.