Universe Expansion Calculator

Hubble’s Law and Cosmic Expansion

Hubble’s Law states that galaxies recede from us at a speed proportional to their distance: v = H₀ × d, where H₀ is the Hubble constant (currently measured around 67–73 km/s/Mpc depending on method) and d is the galaxy’s distance in megaparsecs.

This relationship is direct evidence that the universe is expanding — it’s not that galaxies are moving through static space, but that space itself is stretching between them. At large enough distances, this apparent recession velocity can approach or even formally exceed the speed of light, which is permitted because it reflects the expansion of space rather than motion through it.