What this calculator does
Hubble's Law works out recession speed of a distant galaxy from its distance and the Hubble constant. Enter your own figures above and the answer updates as you type: nothing is fixed in the code, so the result reflects exactly the numbers you supply.
The formula this calculator evaluates is printed under the tool and explained below, so you can check the working by hand or reuse it in a spreadsheet.
The formula
Formulav = H0 × d, Hubble time tH = 1/H0
The inputs explained
| Field | What to enter |
|---|---|
| Hubble constant (H0) (km/s/Mpc) | A number, measured in km/s/Mpc. Starts at 70. |
| Distance to galaxy (d) (Mpc) | A number, measured in Mpc. Starts at 100. |
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the answer changes with hubble constant (h0)
Every other input is held at the calculator’s starting values while hubble constant (h0) varies. Select any row to load that scenario into the calculator.
How the answer changes with hubble constant (h0)
| Hubble constant (H0) (km/s/Mpc) | Recession velocity (v) | As a fraction of light speed | Hubble time (1/H0) |
|---|---|---|---|
| 35 | 3,500.0 km/s | 1.17% | 27.94 billion years |
| 52.5 | 5,250.0 km/s | 1.75% | 18.62 billion years |
| 70 | 7,000.0 km/s | 2.33% | 13.97 billion years |
| 105 | 10,500.0 km/s | 3.50% | 9.31 billion years |
| 140 | 14,000.0 km/s | 4.67% | 6.98 billion years |
| 210 | 21,000.0 km/s | 7.00% | 4.66 billion years |