Wavelength to Frequency Calculator
Convert between wavelength and frequency for light, sound or any wave speed.
Formula and sources updated · Data sources · 1View algorithm, constants and default inputs (JSON)
About this calculator
For a selected wave speed, wavelength and frequency are inversely related. Enter a positive wavelength or frequency, depending on which value you want to solve for. Preset speeds are simplified values; the broad band labels are illustrative. Photon energy is shown only for electromagnetic waves.
Worked example
calculated with the default values below
Solve for Frequency from wavelength · Wavelength 0.5 m · Frequency 600,000,000 Hz · Wave type Sound in air (343 m/s) · Custom wave speed 343 m/s Frequency 686.000 Hz · Wavelength 0.500000 m · Period 0.001457726 s · Wave speed used 343.00 m/s · Wavelength 500,000,000.00 nm · Band or note Audible range
Method and assumptions
Formula basis and scope
Wavelength × frequency = propagation speed; period = 1 / frequency. The reference supports this wave relationship.
Preset propagation speeds and spectrum boundaries are implementation assumptions; actual sound speed depends on the medium and conditions. Photon energy is returned only for light/radio using Planck’s relation and is outside the cited traveling-wave section.
Data sources
Disclaimer
These calculators give general conversion results. Rounding and the precision of the value you enter both affect the output, so treat displayed decimals as indicative rather than exact.
Implementation source
This record describes the implementation used by this page. It is not independent validation. External references, when available, support only the stated formula or definition; estimates and custom rules retain their own assumptions.
Formula and variables
f = c ÷ λ; T = 1 ÷ f; E = h × f
- c
- Wave speed (m/s)
- λ
- Wavelength (m)
- f
- Frequency (Hz)
- T
- Period (s)
- E
- Photon energy (J)
Solving for wavelength uses λ = c ÷ f. Preset c: sound 343, water 1482, light/radio 299792458; h = 6.62607015×10^-34 J·s; E only for light/radio; band by lookup.
Frequently asked questions
When is photon energy shown?
Photon energy is calculated as h × f only for electromagnetic waves (light and radio in this tool). For sound and water waves the field is blank; a zero photon-energy value would not apply.