Science

Wavelength Calculator

Calculate wavelength from frequency or frequency from wavelength for both electromagnetic and sound waves.

Quick Answer

Wavelength = Speed / Frequency. For EM waves: λ = c / f (c = 299,792,458 m/s). For sound: λ = v / f (v ≈ 343 m/s in air at 20°C).

Results

2.9979 m

Wavelength

100.000 MHz

Frequency

Radio Wave

EM Spectrum

About This Tool

The Wavelength Calculator converts between frequency and wavelength for both electromagnetic (light, radio, X-ray) and sound waves. It uses the fundamental wave equation: wavelength = velocity / frequency.

Electromagnetic Waves

All electromagnetic waves travel at the speed of light in vacuum (c = 299,792,458 m/s). The EM spectrum ranges from radio waves (meters to kilometers) through microwaves, infrared, visible light, ultraviolet, X-rays, to gamma rays (picometers). Frequency and wavelength are inversely proportional.

Sound Waves

Sound travels at about 343 m/s in dry air at 20°C. The speed increases with temperature and in denser media — roughly 1,480 m/s in water and 5,960 m/s in steel. Human hearing ranges from 20 Hz (17 m wavelength) to 20 kHz (17 mm wavelength).

The Electromagnetic Spectrum

Radio waves: >1 mm. Microwave: 1 mm–1 m. Infrared: 700 nm–1 mm. Visible light: 380–700 nm (violet to red). Ultraviolet: 10–380 nm. X-rays: 0.01–10 nm. Gamma rays: <0.01 nm. Each region has unique properties and applications.

Applications

Antenna design requires matching antenna length to the wavelength (or fraction) of the target frequency. Acoustic room treatment uses wavelength to determine absorber thickness. Fiber optics operate at specific wavelengths in the infrared (1310 nm and 1550 nm) for minimal signal loss.

Frequently Asked Questions

What is the relationship between wavelength and frequency?
They are inversely proportional. Wavelength × frequency = wave speed. Double the frequency and the wavelength halves. This relationship holds for all types of waves.
What wavelength is visible light?
Visible light ranges from about 380 nm (violet) to 700 nm (red). Peak human eye sensitivity is around 555 nm (green-yellow). Each color corresponds to a narrow band of wavelengths.
How fast does sound travel?
About 343 m/s (767 mph) in dry air at 20°C. Speed increases about 0.6 m/s per degree Celsius. Sound is much faster in water (~1,480 m/s) and steel (~5,960 m/s).
What is the wavelength of WiFi?
2.4 GHz WiFi has a wavelength of about 12.5 cm. 5 GHz WiFi has a wavelength of about 6 cm. This is why 5 GHz has shorter range — shorter wavelengths are absorbed more easily by walls.
Why does wavelength matter for antennas?
Antenna efficiency peaks when the antenna length matches the wavelength (or a fraction like 1/2 or 1/4). A quarter-wave antenna for FM radio at 100 MHz is about 75 cm long.

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