Hubble's Law Calculator
Calculate recession velocity and distance from cosmological redshift using Hubble's Law. Includes lookback time, scale factor, and relativistic corrections.
Inputs
Results
Recession Velocity (classical)
29,979.25 km/s
Recession Velocity (relativistic)
28,487.07 km/s
Distance
428.27 Mpc
How to Use This Calculator
- Enter the spectroscopic Redshift (z) of the galaxy — nearby galaxies are 0.001–0.1, distant quasars can exceed 6.
- Set the Hubble Constant (H₀) in km/s/Mpc — Planck gives 67.4, SH0ES gives 73.0; 70 is a common compromise.
- Read Distance (Mpc) and Distance (Gly) for the galaxy's comoving distance from Earth.
- Use Lookback Time (Gyr) to determine how far into the past you are observing the object.
- Compare Classical and Relativistic recession velocities — for high-z objects, the relativistic formula is more accurate.
Formula
v = H₀ × d; d = cz / H₀Related Calculators
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