Free Comoving Distance Calculator

Approximate the comoving distance to a galaxy at low redshift using d = c * z / H0, the linearised Hubble relation.

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km/s/Mpc

Comoving Distance

428.2857 Mpc

Distance (Mly)1,396.8967 Mly

Comoving Distance vs Redshift (z)

View formula & how it works →

Comoving Distance Approximation

At low redshifts the comoving distance is well approximated by the linear Hubble relation.

Formula

d = c z / H0

  • *c* = 299 800 km/s (speed of light)
  • *z* = observed redshift
  • *H0* = Hubble constant

    • The result is in Mpc. For z above about 0.3, higher-order corrections become important.

    Example Calculation

    A galaxy at redshift z = 0.1 with H0 = 70 km/s/Mpc.

    1. 01d = c z / H0
    2. 02d = 299800 * 0.1 / 70
    3. 03d = 29980 / 70
    4. 04d ≈ 428.3 Mpc ≈ 1396 Mly

    Frequently Asked Questions

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