Frequency Wavelength Calculator
Convert between RF frequency and wavelength in meters and feet. Essential for antenna design and ham radio band planning.
Built for Ham Radio1 documented formula2 recommended next stepsPrivate in your browser
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A quick decision brief for this specific tool
Inputs that matter
Convert From, Value
Output to expect
Frequency ↔ Wavelength
How it works
1 documented formula across 1 calculation mode
- Confirm that every value uses the unit and time basis shown before comparing scenarios.
- Change one input at a time to see which assumption materially changes the result.
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Reference & details
How it works
Updated July 2026
How it works
Updated July 2026Wavelength 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.