Hubble Distance Calculator Formula

Understand the math behind the hubble distance calculator. Each variable explained with a worked example.

Use the Hubble Distance Calculator

Formulas Used

Distance

distance_mpc = velocity / hubble_constant

Distance (Mly)

distance_mly = velocity / hubble_constant * 3.26156

Variables

VariableDescriptionDefault
velocityRecession Velocity(km/s)7000
hubble_constantHubble Constant (H0)(km/s/Mpc)70

How It Works

Hubble's Law

v = H0 × d or equivalently d = v / H0

  • *v* = recession velocity (km/s)
  • *H0* = Hubble constant (≈70 km/s/Mpc)
  • *d* = distance in megaparsecs

    • This linear relation holds well for galaxies not too far away (z < 0.1). For larger distances, cosmological models are needed.

    Worked Example

    A galaxy recedes at 7 000 km/s with H0 = 70 km/s/Mpc.

    velocity = 7000hubble_constant = 70
    1. 01d = v / H0 = 7000 / 70 = 100 Mpc
    2. 02In Mly: 100 × 3.262 = 326.2 million light-years

    Frequently Asked Questions

    What is the Hubble constant?

    It measures the current expansion rate of the universe. Current estimates range from about 67 to 73 km/s/Mpc depending on the method.

    Why is there a Hubble tension?

    Measurements from the early universe (CMB) give H0 ≈ 67, while local distance-ladder methods give ≈73. The discrepancy is not yet resolved.

    Does Hubble's law mean we are at the centre?

    No. Every point in an expanding universe sees all other points receding. There is no centre.

    Ready to run the numbers?

    Open Hubble Distance Calculator