Wavelength & Frequency Calculator
Wavelength and frequency calculator: v = f·λ for sound, light and radio waves. Find speed, frequency, wavelength and period.
v = f · λ
How to use this calculator
- Choose the quantity you want under “Solve for”.
- Type the known values and pick their units: any combination works.
- The result updates as you type. Open “Show the steps” to see the substitution.
For any wave, speed equals frequency times wavelength, v = f·λ. The period is T = 1/f.
Use 343 m/s for sound in air at 20 °C and 299,792,458 m/s (unit c) for light and radio waves in vacuum.
Formula
v = f · λ
| Symbol | Quantity | Units |
|---|---|---|
| f | Frequency | Hz, kHz, MHz, GHz, THz |
| λ | Wavelength | m, km, cm, mm, µm, nm, pm, Å, in, ft, yd, mi, nmi, au, ly |
| v | Wave speed | m/s, km/h, mph, kn, ft/s, c |
Worked example
Given: f = 440 Hz · λ = 0.78 m
v = f · λ
Result: v = 343.2 m/s
Frequently asked questions
What is the wavelength of a 100 MHz FM radio wave?
λ = c/f = 299,792,458/100,000,000 ≈ 3.00 m.
What is the wavelength of the note A4?
λ = 343/440 = 0.78 m in air at 20 °C.