Hubble Law Calculator: v = H0 x d

How fast a distant galaxy moves away, from its distance.

Calculated from standard textbook formulas, with every step shown. The formulas are fixed, so the working does not need checking: what matters is the numbers you type in. Use these calculators only if you are competent to choose the inputs (loads, material strength, dimensions, supports) and check your units and assumptions. For learning and checking your own working: design and sign-off are for a qualified engineer. Drafting Central does not store the numbers you type.

How this calculator works

Choose which quantity you want to find.

Enter the other values in the units shown.

The calculator gives the answer with the formula, the substituted numbers, and the answer in other units.

Formulas used

  • v = H_0 d
  • d = \frac{v}{H_0}

Worked example

With the default numbers in the calculator above:

  1. The formula, arranged to find the recession speed: recession speed = hubble constant x distance
  2. Put the values in (every value in its SI unit): recession speed = 70 x 100
  3. The answer: recession speed: 7000 km/s
  4. The same answer in other units: 7.0e+6 m/s

Change the numbers in the calculator to see the full working, every step, for your own case.

A second worked example

A different case, with these numbers: What do you want to find? Distance; Recession speed (leave it as it is if this is what you are finding) 7000 km/s; Hubble constant (leave it as it is if this is what you are finding) 70 km/s/Mpc.

  1. The formula, arranged to find the distance: distance = (recession speed) / (hubble constant)
  2. Put the values in (every value in its SI unit): distance = (7000) / (70)
  3. The answer: distance: 100 Mpc
  4. The same answer in other units: 326.156 million light years

Common questions

What is Hubble's law?

The farther away a galaxy is, the faster it moves away from us. The speed is the Hubble constant times the distance.

What is the Hubble constant?

About 70 km/s per megaparsec, so a galaxy 100 Mpc away recedes at 7000 km/s.

How old is the universe from the Hubble constant?

The reciprocal of the Hubble constant is about 14 billion years, close to the measured age.

Related calculators

Got a question about this? Ask an engineering question and get a plain-language answer with references.

Further reading: Any astronomy or physics text (Hubble's law).

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