Doppler Shift Calculator
Calculate the Doppler effect for sound and light.
Find the observed frequency when source or observer is moving.
Doppler Shift Result
The Doppler effect is the change in frequency (or wavelength) of a wave when the source and observer are moving relative to each other.
For sound waves:
f_observed = f_source × (v_sound + v_observer) / (v_sound + v_source)
Where:
- f_source = frequency emitted by the source (Hz)
- v_sound = speed of sound (~343 m/s or 1,125 ft/s at sea level)
- v_observer = speed of observer (positive if moving toward source)
- v_source = speed of source (positive if moving away from observer)
Example: An ambulance siren at 700 Hz approaching you at 30 m/s:
- f_observed = 700 × (343 + 0) / (343 - 30) = 700 × 343/313 = 767 Hz (higher pitch)
- After it passes: 700 × 343/373 = 644 Hz (lower pitch)
For light (redshift/blueshift):
- Objects moving away show redshift (longer wavelength)
- Objects moving toward show blueshift (shorter wavelength)
- Used in astronomy to measure star and galaxy velocities