# Hubble’s Law Calculator

URL: https://speedycalculator.com/calculators/physics/hubbles-law/
Last updated: 2026-10-30

> The Hubble's law calculator finds the recession velocity of a distant galaxy from its distance and the Hubble constant (or the distance from the velocity), plus the approximate redshift and Hubble time.

## Inputs

- Find
- Hubble constant H₀ (km/s/Mpc)
- Distance d (Mpc, Mly, ly)
- Recession velocity v (km/s, c, m/s)

## Results

- Recession velocity
- Distance
- Approximate redshift z
- Hubble time

## Formula

```
v = H₀·d,  z ≈ v/c (for v ≪ c),  Hubble time t_H = 1/H₀
```

## Explanation

In 1929 Edwin Hubble found that distant galaxies recede faster the farther away they are – the universe is expanding. The Hubble constant is about 67–73 km/s per megaparsec, depending on the method (the "Hubble tension").

### How to use the Hubble's Law Calculator

- **Find**
- **Hubble constant H₀ (km/s/Mpc)**
- **Distance d**
- **Recession velocity v**

Results update as you type, every field has its own unit menu, and everything is calculated in your browser.

### How it works

Choose what to find, enter the Hubble constant and the distance or velocity.

### Inputs explained

FieldWhat to enterFindChoose one: Recession velocity, DistanceHubble constant H₀ (km/s/Mpc)A numberDistance dUnits: Mpc, Mly, lyRecession velocity vUnits: km/s, c, m/s

### What each result means

- **Recession velocity** = [H0 SI]×[Distance d]
- **Distance** = [Recession velocity v]÷[H0 SI]
- **Hubble time** = 1÷[H0 SI]

### Example values

How the main result changes when **Hubble constant H₀** changes and everything else stays at the example values above:

Hubble constant H₀ (km/s/Mpc)Recession velocity (km/s)353,50052.55,250707,00087.58,75010510,50014014,000

## Worked example

Inputs — Find: Recession velocity; Hubble constant H₀ (km/s/Mpc): 70; Distance d: 100 Mpc.

Results — **Recession velocity = 7,000 km/s**; Approximate redshift z = 0.02335; Hubble time = 13.9685 Gyr.

## Key terms

- **Megaparsec**: One million parsecs, about 3.26 million light-years.

## FAQ

**What is the Hubble constant?**
The current expansion rate of the universe, about 70 km/s/Mpc.

**What is the Hubble tension?**
Different methods give ~67 and ~73 km/s/Mpc.

**Can galaxies recede faster than light?**
Yes, at great distances – space itself expands.

**Is the Hubble time the age of the universe?**
It is close (about 14 Gyr), but the true age depends on how expansion changed.


## Sources

- [OpenStax – Astronomy 2e](https://openstax.org/details/books/astronomy-2e)
- [NASA – Planetary fact sheet](https://nssdc.gsfc.nasa.gov/planetary/factsheet/)