Wavelength Calculator
Convert frequency to wavelength (and back) in vacuum, air, or water. Identify the electromagnetic spectrum band, calculate photon energy, and find de Broglie wavelength.
Wavelength
—
Wavelength —
Period —
Wave Number —
Extended More scenarios, charts & detailed breakdown ▾
Wavelength (m)
—
Wavelength (cm) —
Wavelength (nm) —
Period (T) —
Professional Full parameters & maximum detail ▾
Wave Properties
Wavelength —
Photon Properties
Photon Energy (J) —
Photon Energy (eV) —
Photon Momentum —
Matter Wave & Doppler
de Broglie Wavelength —
Doppler Shifted Freq —
Quarter-Wave Antenna —
How to Use This Calculator
- Enter the frequency value and select the unit (Hz, kHz, MHz, or GHz).
- Select the medium (vacuum, air, or water).
- Click Calculate to see wavelength, period, and wave number.
- Use Extended tabs to convert wavelength→frequency or identify the EM spectrum band.
Formula
λ = v ÷ f T = 1 ÷ f k = 2π ÷ λ
v (vacuum) = 2.998×10⁸ m/s | v (water) = v ÷ 1.333
Example
Example: f = 500 MHz in vacuum → λ = 2.998×10⁸ ÷ 5×10⁸ = 0.600 m (60 cm)
Frequently Asked Questions
- They are inversely proportional: λ = v ÷ f, where v is wave speed, f is frequency, and λ is wavelength. Higher frequency means shorter wavelength.
- In vacuum, c = 299,792,458 m/s. In air it is slightly less (~299,700,000 m/s). In water it is c ÷ 1.33 ≈ 225,408,000 m/s due to the refractive index.
- E = hf, where h = 6.626×10⁻³⁴ J·s (Planck's constant). For example, green light at 550 nm (5.45×10¹⁴ Hz) has energy ≈ 3.61×10⁻¹⁹ J ≈ 2.25 eV.
- All matter has a wave nature with wavelength λ = h ÷ (mv), where m is mass and v is velocity. This is significant only for subatomic particles.
- The observed frequency shifts when source or observer moves. For a moving source: f_obs = f × v ÷ (v ± v_source). Ambulance sirens and redshift of galaxies are classic examples.