frequency and wavelength calculator

What this frequency and wavelength calculator does

This calculator helps you quickly solve one unknown wave value when you know the other two. It works for electromagnetic waves (like radio, microwaves, visible light) and mechanical waves (such as sound in air, water, or solids), as long as you use the correct wave speed for the medium.

The core formula

Wave equation

The relationship between wave speed, frequency, and wavelength is:

v = f × λ

• v = wave speed (meters per second, m/s)
• f = frequency (hertz, Hz)
• λ = wavelength (meters, m)

From that one formula, you can rearrange to solve for any variable:

• λ = v / f
• f = v / λ
• v = f × λ

How to use the calculator

Step-by-step

• Select what you want to calculate: wavelength, frequency, or speed.
• Enter the known values in the visible input fields.
• Choose the correct units for each value.
• Click Calculate to see the answer and unit conversions.

The tool automatically converts units to SI units internally, performs the calculation, and then shows a readable result with helpful alternate units.

Examples

Example 1: Wavelength from frequency

If frequency is 100 MHz and wave speed is the speed of light in vacuum, the wavelength is approximately 3 meters.

Example 2: Frequency from wavelength

If wavelength is 500 nm (green light) and wave speed is 299,792,458 m/s, frequency is about 5.996 × 10¹⁴ Hz.

Example 3: Speed from frequency and wavelength

If a sound wave has frequency 440 Hz and wavelength 0.78 m, speed is about 343 m/s, which is typical for air near room temperature.

Common unit notes

• 1 kHz = 1,000 Hz
• 1 MHz = 1,000,000 Hz
• 1 GHz = 1,000,000,000 Hz
• 1 cm = 0.01 m
• 1 mm = 0.001 m
• 1 nm = 0.000000001 m

Why medium matters

For electromagnetic waves, speed in vacuum is constant (c). In materials such as glass or water, the wave speed is lower, so wavelength changes while frequency remains constant across boundaries. For sound waves, speed depends strongly on temperature, pressure, and material density.

Quick troubleshooting

If you get an error

• Make sure all required inputs are filled.
• Values must be positive numbers greater than zero.
• Double-check units (for example, nm vs mm makes a huge difference).