Frequency and Wavelength Calculator
Find the wavelength for a frequency, or the frequency for a wavelength.
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Wavelength (m)
Wavelength (m)
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Wavelength (cm)
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Period (ns)
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Quarter wavelength (m)
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Frequency and Wavelength Calculator by TheCalcTools
How the Frequency and Wavelength Calculator works
Enter a frequency in megahertz and choose the medium.
Wavelength is the wave speed divided by frequency.
The quarter-wave length is handy for antenna design.
The formula
λ = v ÷ fT = 1 ÷ f
Worked example
Using the default values shown in the calculator:
| Frequency (MHz) | 100 |
|---|---|
| Medium | Light / radio in vacuum |
- λ = 299,792,458 ÷ (100 × 10⁶) = 2.9979 m.
- The period is 10 ns.
- A quarter wavelength is 0.7495 m.
Result:
| Wavelength (m) | 2.9979 |
|---|---|
| Wavelength (cm) | 299.79 |
| Period (ns) | 10.000 |
| Quarter wavelength (m) | 0.7495 |
Frequently asked questions
How long is a quarter-wave antenna?
A quarter of the wavelength, reduced by a velocity factor of roughly 0.95 for real wire. At 100 MHz that is about 0.71 m.
Does the wavelength change in a medium?
Yes. The frequency stays the same but the speed drops, so the wavelength shortens.
Sources and further reading
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This calculator gives estimates for information only. Check important results independently before you rely on them. See our disclaimer.