Doppler Effect Calculator
Calculate doppler effect instantly in your browser — the published formula, worked locally with no data sent anywhere.
Loading calculator…
What this tool does
Calculate doppler effect instantly in your browser — the published formula, worked locally with no data sent anywhere. Classical (non-relativistic) Doppler effect for sound in still air. For light and other EM waves the relativistic formula is needed — the redshifts of galaxies use that version.
How to use the Doppler Effect Calculator
- Enter or select source frequency (hz).
- Enter or select motion.
- Enter or select observer speed (m/s).
- Enter or select source speed (m/s).
- Enter or select speed of sound (m/s).
- Read the calculated result; change any measurement to compare alternatives.
Formula
observed frequency f′ = f × (v ± v_observer) / (v ∓ v_source): plus/faster signs when approaching, reversed when receding (v = speed of sound, 343 m/s in 20 °C air).
- freq
- Source frequency (Hz)
- dir
- Motion
- vObs
- Observer speed (m/s)
- vSrc
- Source speed (m/s)
- vSound
- Speed of sound (m/s)
Classical (non-relativistic) Doppler effect for sound in still air. For light and other EM waves the relativistic formula is needed — the redshifts of galaxies use that version.
Worked example
For doppler effect calculator, the following measurements illustrate the exact method: Source frequency (Hz): 500; Motion: approach; Observer speed (m/s): 0; Source speed (m/s): 30; Speed of sound (m/s): 343.
Inputs
- Source frequency (Hz)500
- MotionSource and observer moving toward each other
- Observer speed (m/s)0
- Source speed (m/s)30
- Speed of sound (m/s)343
Result
- Observed frequency (Hz)547.92
- Frequency shift (Hz)47.92
- Shift (%)9.58
- Wavelength in front of the source (m)0.63
Results explained
- Observed frequency (Hz)
- Observed frequency (Hz) from the formula above. Classical (non-relativistic) Doppler effect for sound in still air. For light and other EM waves the relativistic formula is needed — the redshifts of galaxies use that version.
- Frequency shift (Hz)
- Frequency shift (Hz) from the formula above. Classical (non-relativistic) Doppler effect for sound in still air. For light and other EM waves the relativistic formula is needed — the redshifts of galaxies use that version.
- Shift (%)
- Shift (%) from the formula above. Classical (non-relativistic) Doppler effect for sound in still air. For light and other EM waves the relativistic formula is needed — the redshifts of galaxies use that version.
- Wavelength in front of the source (m)
- Wavelength in front of the source (m) from the formula above. Classical (non-relativistic) Doppler effect for sound in still air. For light and other EM waves the relativistic formula is needed — the redshifts of galaxies use that version.
Frequently asked questions
observed frequency f′ = f × (v ± v_observer) / (v ∓ v_source): plus/faster signs when approaching, reversed when receding (v = speed of sound, 343 m/s in 20 °C air).
Classical (non-relativistic) Doppler effect for sound in still air. For light and other EM waves the relativistic formula is needed — the redshifts of galaxies use that version.
Every field is labelled with its unit — enter values in exactly the labelled unit and read the result in the labelled output unit. Fields with a unit symbol also support the site-wide imperial/metric switch, which converts before the formula runs.
It uses double-precision arithmetic and the published constants and formulas named on this page. The last displayed digit may be rounded, and real conditions can differ from the idealized model described in the assumptions.
Yes. Every calculation runs entirely in your browser; nothing you enter is uploaded, stored or shared.