Waves & Optics
Doppler Effect Calculator
Calculate the observed frequency shift when a source or observer is moving. Works for sound in any medium. Includes real-world examples like ambulance sirens and police radar.
f' = f × (v ± vo) / (v ∓ vs)
Enter source frequency and speeds to calculate.
Real-world examples
Doppler equation
f' = f × (v ± v_o) / (v ∓ v_s)
Use + for v_o when observer moves toward source; use − for v_s when source moves toward observer. Reversed signs for moving away. v is the wave speed in the medium. For light (relativistic Doppler), the equation differs — it is used for redshift/blueshift in astronomy.