Hubble's Law Velocity Calculator

The discovery that revealed an expanding universe

Hubble's Law states that galaxies recede from us at a speed directly proportional to their distance - the farther away a galaxy is, the faster it appears to be moving away, a relationship that revealed the universe itself is expanding.

Worked example

For a galaxy 100 megaparsecs away, using a Hubble constant of 70 km/s/Mpc:

v = 70 x 100 = 7,000.0 km/s

Frequently asked questions

Why isn't the Hubble constant a single agreed-upon number? Different measurement methods (based on nearby "standard candle" stars versus the cosmic microwave background) currently give slightly different values, typically clustering between 67-73 km/s/Mpc - this unresolved discrepancy is known in cosmology as the "Hubble tension."

Does this mean distant galaxies are moving through space faster than light? At very large distances, calculated recession velocities can exceed the speed of light - but this reflects the expansion of space itself, not objects moving through space, which is why it does not violate relativity's speed limit on motion through space.