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Frequency Wavelength Calculator

Convert between RF frequency and wavelength in meters and feet. Essential for antenna design and ham radio band planning.

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Inputs that matter
Convert From, Value
Output to expect
Frequency ↔ Wavelength
  • Check the units and required inputs before comparing results.
  • Keep the assumptions with a copied result so you can reproduce the calculation later.
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Reference & details

How it works

Wavelength from Frequency

Speed of light (3×10⁸ m/s) divided by frequency. 7 MHz → 42.86 meters. Free space approximation.

λ (m) = 300 ÷ f (MHz)

Frequency from Wavelength

Reverse calculation. A 20-meter band wavelength corresponds to approximately 15 MHz (actually 14.0–14.35 MHz band).

f (MHz) = 300 ÷ λ (m)

Feet Conversion

Imperial formula for antenna calculations. 14 MHz → 70.3 feet full wavelength.

λ (ft) = 984 ÷ f (MHz)

Updated: July 2026

Example Scenarios

20-meter wavelength = 300 ÷ 14.2 ≈ 21.1 meters. Band name corresponds to approximate wavelength in meters.

Director spacing at 0.15λ on 144 MHz: λ = 2.08m, spacing = 0.31m (12.2 inches) between elements.

At 1.8 MHz (160m), wavelength 166m — ground wave propagation dominant. At 28 MHz, 10.7m wavelength enables sporadic-E skip.

FAQ

Historical convention from early radio when wavelength was easier to measure than frequency. 20-meter band ≈ 20m wavelength (14 MHz). Names are approximate.

Wavelength in meters equals 300 divided by frequency in MHz. Derived from c = fλ where c ≈ 3×10⁸ m/s, simplified for MHz and meters.

In free space, yes — formula is exact. In coax, wire, or other media, effective wavelength is shorter by the velocity factor of that medium.

Antenna elements are fractions of wavelength: half-wave = λ/2, quarter-wave = λ/4. Use 468/f (feet) or 300/f (meters) for half-wave dipole.

300 ÷ 2400 = 0.125 meters = 12.5 cm. Quarter-wave antenna element ≈ 3.1 cm. Same physics applies to all RF frequencies.

About Frequency Wavelength Calculator

Frequency and wavelength are inversely related through the speed of light. Enter frequency in MHz or wavelength in meters to convert between units for antenna design, propagation analysis, and frequency-to-band identification.