Wavelength Calculator 2026
Convert between wavelength, frequency, wave speed and period for any wave type — light, radio, sound, microwaves and more. Instant results across all SI units.
Wave Parameters
Choose what to solve for, then enter the two known values
Enter frequency and wave speed to find wavelength.
Preset fills wave speed. Override with custom value below.
Speed of light in vacuum: 299,792,458 m/s
Wave Result
Wavelength, frequency, period & spectrum classification
Enter your known wave values above and click Calculate to see wavelength, frequency, period, and where it sits on the electromagnetic spectrum.
Electromagnetic Spectrum & Wavelengths
The full electromagnetic spectrum arranged by wavelength and frequency. All travel at the speed of light (c ≈ 3 × 10⁸ m/s) in a vacuum.
| Wave Type | Wavelength Range | Frequency Range | Common Applications |
|---|---|---|---|
| Gamma Rays | < 10 pm | > 30 EHz | Cancer treatment, nuclear physics |
| X-Rays | 10 pm – 10 nm | 30 PHz – 30 EHz | Medical imaging, security scanning |
| Ultraviolet (UV) | 10 – 380 nm | 790 THz – 30 PHz | Sterilisation, tanning, forensics |
| Visible Light | 380 – 700 nm | 430 – 790 THz | Human vision, photography, lasers |
| Infrared (IR) | 700 nm – 1 mm | 300 GHz – 430 THz | Thermal imaging, remote controls, fibre optics |
| Microwaves | 1 mm – 1 m | 300 MHz – 300 GHz | WiFi, radar, microwave ovens, 5G |
| Radio Waves | > 1 m | < 300 MHz | AM/FM radio, TV broadcast, satellite |
Wavelength Calculator FAQ
Answers to common questions about wavelength, frequency, wave speed, and the electromagnetic spectrum.
The wavelength formula is λ = v / f, where λ (lambda) is the wavelength in metres, v is the wave speed in metres per second, and f is the frequency in hertz. For electromagnetic waves in a vacuum, v equals the speed of light (approximately 299,792,458 m/s).
Visible light spans wavelengths from approximately 380 nm (violet) to 700 nm (red). Within this range: violet is 380–450 nm, blue is 450–495 nm, green is 495–570 nm, yellow is 570–590 nm, orange is 590–620 nm, and red is 620–750 nm.
To convert frequency to wavelength, divide the wave speed by the frequency: λ = v / f. For radio waves and light in a vacuum, use v = 299,792,458 m/s. For sound in air at 20°C, use v ≈ 343 m/s. For example, a 100 MHz FM radio signal has a wavelength of approximately 3 metres.
The speed of light in a vacuum is exactly 299,792,458 metres per second (approximately 3 × 10⁸ m/s). This is denoted as c and is used for all electromagnetic wave calculations including radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays.
Wavelength and frequency are inversely proportional: as frequency increases, wavelength decreases, and vice versa. Their product always equals the wave speed (v = λ × f). This means a high-frequency gamma ray has an extremely short wavelength, while a low-frequency radio wave can be hundreds of metres long.