Frequency to Wavelength Calculator for Radio, Light and Sound
Enter a frequency (Hz to GHz) or a wavelength, and choose the medium. You get the wavelength or frequency, the period and the half-wavelength.
- Nothing you type is stored
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Wavelength
2.998 m
- Frequency
- 100 MHz
- Period
- 10 ns
- Half wavelength
- 1.499 m
- Speed used
- 29,97,92,458 m/s
Show working
- λ = 29,97,92,458 ÷ 10,00,00,000 Hz = 2.998 m
How to use
- Choose whether to find wavelength or frequency.
- Enter the value and its unit.
- Pick the medium: radio/light, sound in air, sound in water or a custom speed.
Good to know
Wavelength λ = speed ÷ frequency, and frequency = speed ÷ wavelength. Radio waves and light travel at 299,792,458 m/s in vacuum (almost the same in air). Period = 1 ÷ frequency.
Sound travels about 343 m/s in air at 20 °C (faster when warmer) and about 1,480 m/s in water, so a 1 kHz tone is 34 cm long in air. FM radio at 100 MHz has a 3 m wavelength; Wi-Fi at 2.4 GHz about 12.5 cm.
The half-wavelength is shown because a half-wave dipole antenna is about that long (usually trimmed to about 95% for the end effect). In cables, waves travel slower (the velocity factor, often 0.66–0.85), so use a custom speed for cable lengths.
Questions
What is the wavelength of 100 MHz FM?
299,792,458 ÷ 100,000,000 = 3.0 m.
What is the wavelength of 2.4 GHz Wi-Fi?
About 12.5 cm.
What is the wavelength of 50 Hz mains?
About 6,000 km in free space.
How long is a 1 kHz sound wave?
About 34.3 cm in air at 20 °C.
What is the period?
The time for one cycle: 1 ÷ frequency. 50 Hz has a 20 ms period.