Your result will appear here
Fill in the fields and press Calculate.
Every wave — light, sound, radio, water ripples — obeys one relation: its speed equals its frequency times its wavelength, v = f × λ. Know any two and the third follows, so you can turn a radio frequency into a wavelength or a musical pitch into a distance.
Choose what you want to find, enter the values you know, and get the result.
Wavelength Calculator: step-by-step worked example
- Solve for
- Wavelength (from speed & frequency)
- Wave speed (m/s)
- 299,792,458
- Frequency (Hz)
- 100,000,000
- 1
Wave equation
v = f × λ → λ = v ÷ f
299,792,458 m/s ÷ 100,000,000 Hz = 2.9979 m
- 2
In centimetres
cm = m × 100
2.9979 × 100 = 299.7925 cm
- 3
Period
T = 1 ÷ f
1 ÷ 100,000,000 = 10 ns
- Wavelength:11.9917 m → 1.499 m
Good to know: Use v = 299,792,458 m/s for light and radio, ≈ 343 m/s for sound in air. An FM station at 100 MHz has λ ≈ 3 m, which is why a quarter-wave antenna is ≈ 75 cm.
Wavelength Calculator — how it works
The wave equation
| Solve for | Formula |
|---|---|
| Wavelength λ (m) | speed ÷ frequency |
| Frequency f (Hz) | speed ÷ wavelength |
| Wave speed v (m/s) | frequency × wavelength |
Frequency is in hertz (cycles per second) and wavelength in metres, so the speed comes out in metres per second.
The speed depends on the wave
The wave speed isn't universal — it depends on the type of wave and the medium. Electromagnetic waves (light, radio, Wi-Fi) travel at c ≈ 299,792,458 m/s in a vacuum. Sound in air is far slower, about 343 m/s at room temperature, and changes with temperature and medium. Enter the right speed for your wave.
Frequency and wavelength are inverse
For a fixed speed, higher frequency means shorter wavelength and vice versa. That's why high-pitched sounds and blue light have short wavelengths while bass notes and red light have long ones — and why a 100 MHz FM station has a 3-metre wavelength while 5 GHz Wi-Fi is just 6 cm.
Where it helps
Radio and antenna design (antennas scale with wavelength), acoustics and music, optics and spectroscopy, and physics homework. For light problems, the photon energy also follows from the frequency, but that's a separate calculation.
Worked example
An FM radio station broadcasts at 100 MHz (100,000,000 Hz). Radio is an electromagnetic wave, so v ≈ 299,792,458 m/s, and the wavelength is 299,792,458 ÷ 100,000,000 ≈ 3.0 m. For sound, a 686 Hz note in air (v ≈ 343 m/s) has a wavelength of 343 ÷ 686 = 0.5 m — half a metre between crests.
Frequently asked questions
How do I calculate wavelength?+
Divide the wave speed by the frequency: λ = v ÷ f. For a 100 MHz radio wave at the speed of light, that is about 3 metres.
What wave speed should I use?+
For light and other electromagnetic waves, use c ≈ 299,792,458 m/s. For sound in air, use about 343 m/s at room temperature. The speed depends on the wave type and medium.
How are frequency and wavelength related?+
They are inversely proportional for a fixed speed: v = f × λ. Higher frequency means shorter wavelength, so doubling the frequency halves the wavelength.
How do I find frequency from wavelength?+
Divide the wave speed by the wavelength: f = v ÷ λ. A 0.5 m sound wave in air (343 m/s) has a frequency of 686 Hz.
What is a hertz?+
The hertz (Hz) is one cycle per second — the unit of frequency. A 440 Hz tone vibrates 440 times a second; radio and Wi-Fi run into millions (MHz) and billions (GHz) of hertz.
About this page
- Publisher:
- Kalkoro — Teknolojig Bilişim Teknolojileri A.Ş., İstanbul
- Written by:
- Ahmet Tur — Editor (Math, date & time, unit conversion, physics & chemistry, everyday tools)
- Reviewed by:
- Kübra Yıldız — Editor
Parameters come from official sources; the last update date is shown at the bottom of the page.
Spotted a wrong result? Use the "Report a bug" button at the top of the page; every report is reviewed.
How we calculate and our accuracy policy →
Results are for information only. For official matters the relevant authority's calculation prevails.
Last updated: