OrbitLab

Hubble Expansion Calculator

The universe's expansion, quantified.

Distance (megaparsecs)

Recession velocity

7,000 km/s

Uses H₀ = 70 km/s/Mpc

What you entered

Distance (megaparsecs): 100

1
v = H₀ × d
70 × 100= 7000 km/s

Result

Recession velocity: 7,000 km/s

At 100 Mpc away, the universe's expansion carries this object away at 7,000 km/s.

Recession velocity from distance under Hubble's law

Velocity equals the Hubble constant times distance. These rows use H0 = 70 km/s per megaparsec.

Distance	In light years	Recession velocity
1 Mpc	3.26 million	70.0 km/s
10 Mpc	32.6 million	700.0 km/s
100 Mpc	326 million	7,000.0 km/s
500 Mpc	1.63 billion	35,000.0 km/s
1,000 Mpc	3.26 billion	70,000.0 km/s
4,000 Mpc	13.0 billion	280,000.0 km/s

Beyond about 4,300 Mpc this gives velocities above the speed of light. That is not a contradiction: space itself expands, and nothing is moving through space faster than light. Measurements of H0 disagree, at roughly 67 from the cosmic microwave background and 73 from supernovae, an unresolved tension.

A straight-line law for the whole universe

Hubble's Law states recession velocity is simply distance multiplied by the Hubble constant (H₀ ≈ 70 km/s per megaparsec) — the farther away a galaxy is, the faster it appears to be receding from us.

Every point sees itself as the center

This isn't galaxies flying through static space away from a central point — it's space itself expanding uniformly everywhere, meaning every observer, anywhere in the universe, would measure the same law relative to themselves.

Frequently asked questions

A galaxy is 200 Mpc away — how fast is it receding?

v = H₀ × d = 70 km/s/Mpc × 200 Mpc = 14,000 km/s. That is about 4.7% of the speed of light.

How is the Hubble expansion calculator different from the redshift calculator?

The Hubble calculator converts distance directly into recession velocity using v = H₀d. The redshift calculator converts observed wavelength shift into recession velocity. Both measure the same expansion phenomenon from different starting data.

What is the Hubble constant exactly?

About 70 km/s per megaparsec, meaning for every megaparsec (3.26 million light-years) farther away a galaxy is, it recedes 70 km/s faster. The exact value is still debated between different measurement methods (67-73 km/s/Mpc).

Can galaxies recede faster than light?

Yes — very distant galaxies are receding faster than c due to the expansion of space itself. This does not violate special relativity, which forbids faster-than-light travel through space, not the stretching of space itself.