PhysicsCalcs
Waves & Sound

Frequency to Wavelength Calculator

Convert frequency to wavelength using λ = v/f for light, sound, RF, Wi-Fi, and custom wave speeds.

Interactive calculator

Wave Frequency & Wavelength Calculator

Convert frequency to wavelength, wavelength to frequency, wave speed, and period using v = fλ.

Wave speed preset
λf, v

Quick Guide

  • Enter frequency and select units (Hz, MHz, GHz).
  • Choose wave speed: light, sound, or custom.
  • Try example presets (440 Hz, 2.4 GHz).
  • Review wavelength, period, and formula.

Table of Contents

Key Takeaways

  • Frequency and wavelength are related by v = fλ.
  • Wavelength λ = v / f.
  • Higher frequency means shorter wavelength when wave speed is constant.
  • Electromagnetic waves in vacuum use c = 299,792,458 m/s.
  • Sound wavelength depends on the speed of sound in the medium (~343 m/s in air at 20°C).

What Is a Frequency to Wavelength Calculator?

It converts frequency into wavelength using wave speed. Useful for physics, RF, antennas, Wi-Fi, optics, and acoustics learning.

For the reverse conversion, use the Wavelength to Frequency Calculator.

Frequency to Wavelength Formula

Frequency fSpeed vWavelength λv = f × λλ = v / ff = v / λ
λ=v/fλ = v / f

λ = wavelength, v = wave speed, f = frequency in Hz.

Light vs Sound Waves

Electromagnetic waves in vacuum travel at c = 299,792,458 m/s. Sound needs a medium and travels at ~343 m/s in air at 20°C — temperature and humidity affect this value.

Examples

100 MHz (RF)

λ = 299,792,458 / 10⁸ ≈ 2.998 m.

2.4 GHz (Wi-Fi)

λ ≈ 0.125 m = 12.5 cm.

440 Hz (A4 note)

λ = 343 / 440 ≈ 0.78 m in air at 20°C.

RF Band Reference (free space)

Band / signalFrequencyWavelength (approx.)
AM radio1 MHz≈ 300 m
FM radio100 MHz≈ 3 m
Wi-Fi 2.4 GHz2.4 GHz≈ 12.5 cm
5G (mid-band)3.5 GHz≈ 8.6 cm
Sound in air1 kHz≈ 0.343 m

Limitations

Uses ideal wave equations. Sound speed varies with temperature and humidity. RF wavelength in materials depends on refractive index. Educational tool only.

FAQ

What is the formula for wavelength from frequency?›

λ = v / f, where v is wave speed and f is frequency in Hz.

What is the wavelength of 100 MHz?›

In vacuum, λ = 299,792,458 / 100,000,000 ≈ 2.998 m. This is in the FM radio band.

What is the wavelength of 2.4 GHz?›

In vacuum/air approximation, λ ≈ 0.125 m = 12.5 cm. This is why Wi-Fi antennas are small.

What speed should I use for sound?›

Use ~343 m/s for air at 20°C. Sound speed varies with temperature, humidity, and medium (water: ~1,480 m/s, steel: ~5,960 m/s).

Why does higher frequency mean shorter wavelength?›

When v is fixed, λ and f are inversely proportional: λ = v/f. Doubling the frequency halves the wavelength.

Can this be used for antenna design?›

It gives free-space wavelength for education. A half-wave dipole is λ/2. Real antenna design also requires velocity factor and impedance matching.

What is the wavelength of 5G mmWave?›

5G mmWave at 28 GHz has a wavelength of about 10.7 mm, and at 39 GHz about 7.7 mm. These short wavelengths enable very high data rates but have limited range.

What is the wavelength of visible light?›

Visible light ranges from about 380 nm (violet) to 750 nm (red). Red light has the longest wavelength and lowest frequency; violet has the shortest wavelength and highest frequency.

Sources

  1. NIST: speed of light (CODATA)
  2. OpenStax College Physics: Waves
Manish Kumar

Author & technical reviewer

Manish Kumar

PhysicsCalcs tools are reviewed with an educational focus: clear formulas, transparent assumptions, and practical context for students and science learners.

Learn more about Manish