Practical tools for measured work
Doppler shift calculator
Calculate acoustic or longitudinal relativistic Doppler shifts with explicit velocity signs.
Calculate the layout, check the diagram, then print the result for the shop or jobsite.
How it works
Sound: observed frequency = emitted frequency × (sound speed + observer velocity)/(sound speed − source velocity). Positive entered velocities mean moving toward each other. Light: observed frequency = emitted frequency × √((1 − β)/(1 + β)); positive β means recession.
Current-input example
The result above uses these exact values. This snapshot is included when the page is printed so the output can be checked against the original measurements.
- Doppler model
- Sound in a stationary medium
- Emitted frequency
- 1000 Hz
- Sound speed in medium
- 340 m/s
- Observer velocity toward source
- 0 m/s
- Source velocity toward observer
- 34 m/s
Primary result: Observed frequency: 1111.111111 Hz.
Before using the result
- Check the selected mode, units and input values before using the result.
- Read the assumptions and rounding rules; compare the worked example with your intended calculation.
- A numerical result does not supply missing context or change the stated limitations.
Limitations
Both models assume motion along the line of sight. Sound velocities are relative to a stationary medium and must be subsonic in magnitude. Light requires −1 < β < 1. The sound formula must not be used for light.
Frequently asked questions
What should I verify before using this result?
Check the input values, units, dates and assumptions. Compare the method and its stated limits with the source relevant to your task.
Why might the finished result differ?
Results depend on the entered data and the model’s assumptions. Rounding, changing conditions or omitted factors can affect the comparison. Read the limitations before using the result.
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