Frequency & Wavelength Calculator
Convert between frequency and wavelength for sound or radio waves using the speed of propagation, free in your browser.
Enter Values
Minimum 0
How to use this calculator
- Enter either the frequency (Hz) or the wavelength (m) — whichever you know.
- Optionally set the wave speed (default 343 m/s, sound in air at 20 °C).
- Read the other value plus the period of one cycle.
How it works
The Frequency & Wavelength Calculator relates how often a wave repeats (frequency) to how long one cycle is in space (wavelength), using wavelength = wave speed ÷ frequency.
For sound in air the speed is about 343 m/s; for water use ~1500 m/s, and for radio or light use about 3×10⁸ m/s. The period is simply 1 ÷ frequency — the time for one full cycle.
Worked example
Concert-pitch A (440 Hz) in air. Wavelength = 343 ÷ 440 ≈ 0.78 m, and the period is about 2.27 ms.
Frequently asked questions
What wave speed should I use?
It depends on the medium: about 343 m/s for sound in air at 20 °C, roughly 1500 m/s in water, and about 3×10⁸ m/s for radio waves and light. Set the speed field to match.
What is the period?
The period is the time for one complete cycle of the wave, equal to 1 ÷ frequency. A 440 Hz tone has a period of about 2.27 milliseconds.
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Cite this tool
Zerdly. (2026). Frequency & Wavelength Calculator. Retrieved from https://www.zerdly.com/tools/frequency-wavelength-calculator/
Tip: Enter any known values to calculate the remaining results.
All calculations run in your browser. Your inputs are never saved or transmitted.