Wavelength / Frequency Calculator — Speed of Light | RFCalcLab
Convert between RF frequency and wavelength with high precision. Essential for antenna dimensioning and waveguide design. Supports MHz, GHz, and optical wavelengths for telecom and hobbyist radio.
How to Use the Wavelength Converter
Enter either the frequency or the wavelength. The tool applies the relationship λ = c / f, using the exact speed of light in vacuum (c = 299,792,458 m/s), to perform the conversion instantly. Frequency and wavelength are inversely proportional, so doubling the frequency halves the wavelength. As a quick mental check, 300 MHz corresponds to almost exactly 1 metre, and 2.4 GHz (a common Wi-Fi band) works out to about 12.5 cm.
Wavelength is critical for antenna design; for example, a half-wave dipole is sized at roughly λ/2 and a quarter-wave monopole at λ/4 of the target frequency. At 300 MHz the free-space wavelength is about 1.0 m, so a half-wave dipole element is near 50 cm before applying the end-effect shortening factor (typically 0.95). Higher frequencies produce physically smaller antennas, which is why microwave and millimetre-wave hardware is so compact.
You can switch between units such as MHz, GHz, metres, and millimetres to suit your specific engineering needs. Remember that inside cables and dielectric substrates the wave travels slower than in vacuum: the velocity factor (often 0.66 to 0.85 for coax) shortens the guided wavelength accordingly, which matters when cutting matching stubs or phasing lines. This converter reports the free-space value, so divide by the velocity factor when working with physical transmission-line lengths.
Related Topics
- wavelength calculator
- frequency calculator
- RF wavelength
- microwave frequency
- antenna length
Frequently Asked Questions
- How is wavelength related to frequency?
- Wavelength (λ) and frequency (f) are inversely proportional, related by the speed of light (c): λ = c / f. Higher frequencies have shorter wavelengths.
- Does light speed change in cables?
- Yes. In cables or substrates, the signal travels slower than in a vacuum. This is defined by the Velocity Factor (VF), usually around 0.66 to 0.85 for coaxial cables, which effectively shortens the wavelength.
- What is a quarter-wave antenna?
- A quarter-wave antenna is a common monopole design where the radiator length is exactly 1/4 of the target frequency's wavelength. It relies on a ground plane to act as the other half of the antenna system.