Hubble's Law Calculator to Calculate Recessional Velocity of Galaxies
Calculate the recessional velocity of distant galaxies using Hubble's Law. Understand cosmic expansion, the Hubble constant, and how redshift reveals the expanding universe.
What is Hubble's Law?
Hubble's Law states that galaxies are moving away from us at speeds proportional to their distance. Proposed by Edwin Hubble in 1929, it was the first observational evidence that the universe is expanding. It underpins modern cosmology including the Big Bang theory and the concept of dark energy.
🌌 Hubble's Law Calculator
Use our free calculator for instant, accurate results.
📐 Formula
v = H₀ × d
v = recessional velocity (km/s), H₀ = Hubble constant ≈ 70 km/s/Mpc, d = distance to galaxy (Megaparsecs, Mpc). 1 Mpc = 3.086×10²² m.
📝 Worked Example
Galaxy at d = 100 Mpc:
v = 70 × 100 = 7,000 km/s (2.3% of speed of light)
At d = 4,300 Mpc: v ≈ c (the observable universe boundary)
📝 How to Use the Calculator
❓ FAQ
What is the Hubble tension?
Different measurement methods give slightly different values of H₀ (67 vs 73 km/s/Mpc). This 'Hubble tension' is one of the biggest open problems in cosmology.
Does Hubble's Law mean galaxies move faster than light?
At very large distances, yes — the space between us and distant galaxies expands faster than c. This is why the observable universe has a boundary (horizon).
Veer Kumavat
Founder & AuthorVeer is a 14-year-old student from Nashik, Maharashtra, who built SciFi Calculators to help students worldwide master STEM subjects. He is passionate about making complex science and math problems accessible through intuitive digital tools.