Wavelength Calculator has been online since 2007. It began as a single page that converted frequency to wavelength and, over the years, picked up a mixed bag of other calculators. In 2026 it was rebuilt around what people actually came here for: wavelength, frequency, photon energy, matter waves and antenna lengths, each with the formula shown and every constant published.
Who runs it
The site is published by Galena Hall, a small independent publisher of education and reference websites.
How it is funded
The calculators are free. The site may carry advertising in future. It sells nothing and takes no payment for placement.
Accuracy
Constants are CODATA 2018 values, exact where the SI defines them so. Refractive indices and sound speeds are the usual textbook figures at visible wavelengths and room temperature; if your work needs a specific wavelength or temperature, use the custom speed option. Found a wrong result? Send us the inputs.
Privacy in one line
Calculations run in your browser. Nothing you type is sent to us. Details in the privacy policy.