Redshift Velocity Calculator Formula

Understand the math behind the redshift velocity calculator. Each variable explained with a worked example.

Use the Redshift Velocity Calculator

Formulas Used

Recession Velocity

velocity_kms = redshift * 299792.458

Hubble Distance (approx)

hubble_distance = redshift * 299792.458 / 70

Variables

VariableDescriptionDefault
redshiftRedshift (z)0.01

How It Works

Redshift and Recession Velocity

For low redshifts (z << 1):

v = z × c where c = 299 792.458 km/s

Combined with Hubble's law v = H0 d gives approximate distance d = v / H0.

For z > 0.3, relativistic corrections are important.

Worked Example

A galaxy has redshift z = 0.01.

redshift = 0.01
  1. 01v = 0.01 × 299 792.458 = 2 998 km/s
  2. 02d ≈ v / H0 = 2998 / 70 = 42.8 Mpc
  3. 03About 140 million light-years.

Ready to run the numbers?

Open Redshift Velocity Calculator