Redshift to Distance Calculator (Hubble Law)
Fill in the values and the answer updates as you type.
How the Redshift to Distance Calculator (Hubble Law) works
Redshift z measures how far a galaxy light is stretched toward red. The recession velocity comes from the relativistic Doppler formula, v = c × ((1+z)² − 1) ÷ ((1+z)² + 1). Hubble law then gives distance = velocity ÷ Hubble constant. Measured values of the constant range from about 67 to 74 km/s/Mpc. The simple law is a good approximation only for fairly nearby galaxies, roughly z below 0.1. Example: with Redshift (z) 0.01 and Hubble constant 70 km/s/Mpc, the result is Recession velocity (km/s) = 2,983; Distance (megaparsecs) = 42.61; Distance (million light-years) = 138.99.
Inputs and results
The Redshift to Distance Calculator (Hubble Law) takes 2 inputs and gives 3 results.
What you enter
- Redshift (z) — starts at 0.01.
- Hubble constant (km/s/Mpc) — starts at 70.
What you get
- Recession velocity (km/s)
- Distance (megaparsecs)
- Distance (million light-years)
Example: Redshift to Distance Calculator (Hubble Law) with the starting values
With redshift (z) 0.01 and hubble constant 70 km/s/Mpc, the calculator returns:
| Recession velocity (km/s) | 2,983 |
|---|---|
| Distance (megaparsecs) | 42.61 |
| Distance (million light-years) | 138.99 |
Change any value above and the results update straight away.
Redshift to Distance Calculator (Hubble Law) FAQ
How do I use the Redshift to Distance Calculator (Hubble Law)?
Enter redshift (z) and hubble constant in the fields, then read recession velocity (km/s), distance (megaparsecs) and distance (million light-years) in the result panel. The answer updates as you type, and you can press Calculate or Enter to refresh it. Use “Copy link” to share your exact numbers with someone else.
What does the Redshift to Distance Calculator (Hubble Law) calculate?
Recession speed and distance of a galaxy from its redshift. It returns recession velocity (km/s), distance (megaparsecs) and distance (million light-years) from the 2 values you provide.
What values does the Redshift to Distance Calculator (Hubble Law) start with?
It opens with redshift (z) 0.01 and hubble constant 70 km/s/Mpc so you can see a working result straight away. Replace them with your own numbers, or press Reset to return to these starting values.
Is the Redshift to Distance Calculator (Hubble Law) free and private?
Yes. It is free, needs no account, and runs in your browser, so nothing you type is sent to or stored on our servers. See the Privacy Policy for details.
Can I rely on the Redshift to Distance Calculator (Hubble Law) for important decisions?
Treat the result as a well-rounded estimate. Real situations often have details a general calculator cannot know, so confirm important decisions with a qualified professional. See the Disclaimer for more.