Redshift distance calculator

Calculate the distance to a galaxy based on its redshift value using Hubble's Law

Input Parameters

Redshift is the ratio of the change in wavelength of light from a distant galaxy to its rest wavelength.

Default value is 70 km/s/Mpc. You can adjust this if using different measurements.

Calculation Results

Calculation Formula

Distance (Mpc) = c × z / H₀

Where:
c = Speed of light (approximately 3 × 10⁵ km/s)
z = Redshift value
H₀ = Hubble Constant

Redshift distance calculator Calculator Usage Guide

Learn how to use the Redshift distance calculator and its working principles

How to use this calculator

  1. Enter the redshift value (z) of the galaxy. This is typically a small number, e.g., 0.01 for nearby galaxies, or much larger for distant quasars.
  2. Enter the Hubble Constant (H₀) in km/s/Mpc. The default value is 70, but you can adjust this if using different astronomical measurements.
  3. Click the "Calculate" button to compute the distance.
  4. The calculator will display the distance in megaparsecs (Mpc) and in million light-years.

Understanding Redshift

Redshift is a phenomenon where the wavelength of light from a distant galaxy is stretched as the universe expands, causing the light to shift toward the red end of the spectrum. The amount of redshift (z) is directly proportional to the distance of the galaxy from Earth.

Important Notes

  • This calculator uses Hubble's Law, which works well for galaxies within a few billion light-years. For very distant objects, relativistic effects need to be considered.
  • The accuracy of the calculation depends on the accuracy of the Hubble Constant used.
  • For professional astronomical work, more complex models that account for dark energy and other cosmological factors are typically used.