Wave Frequency Calculator — Speed, Wavelength, Period & Photon Energy
Whether you are calculating the wavelength of a musical note, the frequency of a radio station, or the energy of a photon of visible light, the wave equation v = fλ is the starting point. The free wave frequency calculator on PublicSoftTools solves for any wave variable in one step.
The Three Wave Equations
The calculator uses three fundamental wave equations:
- v = f × λ — wave speed equals frequency times wavelength
- T = 1 / f — period is the reciprocal of frequency
- E = h × f — photon energy (where h = 6.626 × 10⁻³⁴ J·s is Planck's constant)
These are all you need for most wave physics problems. The calculator automatically selects the right equation based on which two values you provide.
Wave Frequency Ranges
| Wave Type | Frequency | Wavelength |
|---|---|---|
| AM Radio | 530 kHz – 1.7 MHz | 176–566 m |
| FM Radio | 87.5–108 MHz | 2.8–3.4 m |
| Microwave (WiFi 2.4GHz) | 2.4 GHz | 12.5 cm |
| Infrared | 300 GHz – 400 THz | 0.75–1000 µm |
| Visible light | 430–770 THz | 390–700 nm |
| X-rays | 30 PHz – 30 EHz | 0.01–10 nm |
| Human speech (sound) | 85–255 Hz | 1.3–4 m (at 343 m/s) |
| Middle C (musical note) | 261.6 Hz | 1.31 m (at 343 m/s) |
How to Use the Calculator
- Open the wave frequency calculator.
- Choose which variable to solve for using the tabs: v, f, λ, T, or E.
- Enter the values you know. For sound, use v = 343 m/s; for light in a vacuum, use v = 3×10⁸ m/s.
- The result displays with automatic unit scaling (kHz, MHz, nm, etc.).
Advanced Workflows
Converting radio frequency to wavelength
An FM station broadcasts at 98.1 MHz = 98,100,000 Hz. Using λ = v/f: λ = (3×10⁸) / (98.1×10⁶) ≈ 3.06 m. Enter v = 3e8 and f = 98.1e6 in the calculator to confirm. This explains why FM antennas are roughly 75 cm long (one-quarter wavelength).
Photon energy of visible light
Red light at 700 nm = 7×10⁻⁷ m. Frequency: f = c/λ = (3×10⁸) / (7×10⁻⁷) ≈ 4.28×10¹⁴ Hz. Photon energy: E = hf = (6.626×10⁻³⁴) × (4.28×10¹⁴) ≈ 2.84×10⁻¹⁹ J ≈ 1.77 eV. Blue light at 450 nm has higher frequency and thus more energy per photon — this is why blue light causes more photochemical damage than red light.
Musical interval as a frequency ratio
An octave doubles the frequency. Middle C is 261.6 Hz; the C one octave above is 523.3 Hz. In air at 343 m/s, middle C has a wavelength of 343/261.6 ≈ 1.31 m. Use the calculator to confirm that entering f = 261.6 and v = 343 gives λ ≈ 1.31 m.
Common Questions
Does wave speed change in different media?
Yes. The speed of sound in air is ~343 m/s, in water ~1480 m/s, and in steel ~5960 m/s. Light slows down when entering glass or water by a factor called the refractive index. Only frequency stays constant when a wave crosses from one medium to another — wavelength changes proportionally with the speed.
What is the difference between period and frequency?
Period (T) is how long one complete wave cycle takes in seconds. Frequency (f) is how many cycles occur per second. They are exact reciprocals: T = 1/f. A 50 Hz power line has a period of 20 ms; a 1 kHz audio tone has a period of 1 ms.
Calculate Wave Properties Now
Solve for frequency, wavelength, speed, period, or photon energy in one step.
Open Wave Frequency Calculator