What is the wave equation?

The wave equation is v = f × λ, where v is wave speed (meters per second), f is frequency (hertz), and λ (lambda) is wavelength (meters). It applies to all periodic waves.

What is the speed of light I should use?

In a vacuum, the speed of light is approximately 299,792,458 m/s (often rounded to 3 × 10⁸ m/s). In other media, it is slower by a factor of the refractive index.

What is the speed of sound in air?

The speed of sound in dry air at 20°C is approximately 343 m/s. It varies with temperature — roughly 331 m/s at 0°C and increases about 0.6 m/s per degree Celsius.

Why does wavelength decrease as frequency increases?

Because wave speed stays constant in a given medium. Since v = f × λ, if v is fixed and f goes up, λ must go down proportionally to keep the product equal.

What units does this calculator use?

Inputs are in standard SI units (meters per second for speed, hertz for frequency, meters for wavelength). You can enter scientific notation using E notation, e.g. 3e8 for 3 × 10⁸.

Can I use this for light and radio waves?

Yes. For electromagnetic waves in a vacuum, set the wave speed to 3 × 10⁸ m/s (speed of light). The calculator handles very large or very small numbers and displays them in scientific notation when appropriate.

Wavelength Calculator

Name: Wavelength Calculator
Availability: InStock
Author: Nham Vu

Solve for wavelength, frequency, or wave speed using v = f × λ — choose which variable to find and enter the other two.

Wave Equation Solver

v = f × λ | Solve for any variable

Solve for

Wave Speed (v) — m/s

Frequency (f) — Hz

Wavelength (λ) — m

Quick Presets

Enter values and click Calculate

Electromagnetic Spectrum Reference

Type	Wavelength	Frequency
Radio	> 1 mm	< 300 GHz
Microwave	1 mm – 1 m	300 MHz – 300 GHz
Infrared	700 nm – 1 mm	300 GHz – 430 THz
Visible	380 – 700 nm	430 – 790 THz
Ultraviolet	10 – 380 nm	790 THz – 30 PHz
X-ray	0.01 – 10 nm	30 PHz – 30 EHz
Gamma ray	< 0.01 nm	> 30 EHz

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Summary

Solve for wavelength, frequency, or wave speed using v = f × λ — choose which variable to find and enter the other two.

How it works

Select which variable you want to solve for: wavelength, wave speed, or frequency.
Enter the two known values with their units.
Click Calculate — the tool applies v = f × λ to find the unknown.
Read the result with automatic unit conversion for convenient display.
Use the preset wave types (light, sound, radio) for quick reference values.

Use cases

Convert between frequency and wavelength for electromagnetic radiation.
Find the wavelength of a sound wave at a given frequency.
Calculate the speed of a wave from its frequency and wavelength.
Determine radio antenna length based on broadcast frequency.
Understand the relationship between visible light colors and wavelength.
Physics homework and exam preparation.
RF engineering and antenna design reference.
Teaching the wave equation in science classes.

Frequently Asked Questions

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Last updated: 2026-05-23 · Reviewed by Nham Vu