Wavelength Calculator

Wavelength is the distance between successive crests (or troughs) of a wave. It is directly related to frequency and wave speed through one of the most fundamental equations in physics.

Wavelength Formula:

λ = v / f

• λ (lambda) = Wavelength in meters
• v = Wave speed in m/s
• f = Frequency in Hz (cycles per second)

Equivalently: f = v / λ and v = f × λ

For electromagnetic waves (light, radio, X-rays) in vacuum: v = c = 299,792,458 m/s, often rounded to 3.0 × 10^8 m/s. The calculator uses the exact value, so its answers sit about 0.07% below what the rounded figure gives.

Worked example, FM radio: FM station frequency: 101.5 MHz = 101,500,000 Hz Wavelength = 299,792,458 / 101,500,000 = 2.954 meters

A quarter of that is 73.8 cm, which is why an FM whip antenna is about that long. (Strictly, a quarter-wave whip is a monopole working against a ground plane, such as a car roof. A dipole is the half-wave version, two 74 cm arms.)

Worked example, visible light (green): Frequency: 540 THz = 5.40 × 10^14 Hz Wavelength = 299,792,458 / 5.40 × 10^14 = 5.552 × 10^-7 m = 555 nm

That is almost exactly the wavelength the human eye is most sensitive to in daylight, around 555 nm, which is why safety vests and fire trucks are that particular yellow-green.

Electromagnetic spectrum reference:

Sound waves in air (20°C): v_sound = 343 m/s Middle C (261.6 Hz): λ = 343 / 261.6 = 1.31 meters

Energy and wavelength are inversely related: shorter wavelength = higher energy (Planck’s law: E = hf = hc/λ).