Hubble Law Calculator
Compute galaxy recession velocity from distance or distance from recession velocity using Hubble's Law (v = H₀ × d).
Solve for
1 Mpc = 3.086 × 1022 m ≈ 3.26 million light-years
km/s/Mpc
Result
Enter values and press Calculate.
Recession Velocity
—
km/s
Distance
—
Mpc
Redshift (z)
—
v / c
—
Distance (Mly)
—
Note: Recession velocity exceeds ~10% of the speed of light (v/c > 0.1). The linear Hubble approximation is less accurate at these distances; a full relativistic model is recommended.
H0 Comparison
Same input, different published Hubble constant values.
Results appear after calculation.
| H0 | Source | Velocity (km/s) | z |
|---|
Summary
Compute galaxy recession velocity from distance or distance from recession velocity using Hubble's Law (v = H₀ × d).
How it works
- Select the solve mode: calculate velocity from distance, or distance from velocity.
- Enter the known value (distance in Mpc or velocity in km/s).
- Choose a Hubble constant value (H₀) or enter a custom one.
- Read the computed result and the implied redshift (z) in the output panel.
- Use the table to compare results across different H₀ values at once.
Use cases
- Estimate how fast a galaxy at a known redshift is receding from us.
- Convert a measured recession velocity to a cosmological distance in megaparsecs.
- Compare recession velocities under different published Hubble constant values.
- Cross-check textbook cosmology homework problems involving Hubble's Law.
- Understand the scale of the observable universe by experimenting with large distances.
- Demonstrate the relationship between redshift and distance in an astronomy class.
Frequently Asked Questions
Last updated: 2026-07-23 ·
Reviewed by Nham Vu