basic

Relativistic Doppler Shift Calculator

Light-frequency Doppler shift for source velocity β.

Compute the relativistic (radial) Doppler shift of light from a source moving with β = v/c relative to the observer: f_obs / f_src = √((1 − β) / (1 + β)). Reports observed frequency, redshift z, and shifted wavelength.

Dr. Helena Ortiz By Dr. Helena Ortiz
Published Last reviewed 1 min read

Inputs

nm

Results

Enter values and click Calculate to see results.
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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

f_obs / f_src = √((1 − β) / (1 + β)); z = (λ_obs − λ_src) / λ_src.

In depth

Compute the relativistic (radial) Doppler shift of light from a source moving with β = v/c relative to the observer: f_obs / f_src = √((1 − β) / (1 + β)). Reports observed frequency, redshift z, and shifted wavelength.