How to Use the Wavelength & Frequency Converter
Light behaves as a wave that can be described in two equivalent ways: wavelength and frequency. Wavelength is the distance the wave travels in one full oscillation, measured in nanometers (nm). Frequency is how many oscillations happen per second, measured in terahertz (THz). Because the speed of light in a vacuum is constant at about 299,792 km/s, wavelength and frequency are inversely related - a shorter wavelength always means a higher frequency, and vice versa.
The visible spectrum that the human eye can detect spans a narrow range from about 380nm (violet) to 750nm (red). Within that range, colors shift from violet to blue, cyan, green, yellow, orange, and red as wavelength increases, and this calculator shows which color matches the wavelength you enter. Light shorter than 380nm is ultraviolet (UV), and light longer than 750nm is infrared (IR) - both invisible to the naked eye.
Enter a value, choose nm or THz, and the opposite unit plus the corresponding color are calculated instantly. Useful for physics coursework, spectroscopy experiments, checking LED or laser wavelength specs, and studying color theory.
Frequently Asked Questions
The human eye can see light from roughly 380nm (violet) to 750nm (red). Below 380nm is ultraviolet, and above 750nm is infrared - neither is visible to the naked eye.
Since the speed of light is constant (about 299,792 km/s), wavelength and frequency are inversely proportional. Shorter wavelengths (like violet) have higher frequencies, and longer wavelengths (like red) have lower frequencies. The formula is f = c / lambda.