Wave Speed Calculator — v = fλ
Calculate wave speed, frequency, or wavelength for any type of wave. Covers sound in different media, water waves, seismic waves, and electromagnetic waves.
Waves transfer energy without transferring matter. Whether it's sound rippling through air, an earthquake rolling through rock, or light crossing empty space, the same relationship describes them all: wave speed equals frequency times wavelength. The medium determines the speed; frequency and wavelength adjust to match.
The CalcHub wave speed calculator converts between wave speed, frequency, and wavelength for any wave type.
The Formula
v = f × λ- v = wave speed (m/s)
- f = frequency (Hz)
- λ = wavelength (m)
Speed of Waves in Different Media
| Wave type | Medium | Speed |
|---|---|---|
| Sound | Air (20°C) | 343 m/s |
| Sound | Water | 1480 m/s |
| Sound | Steel | 5100 m/s |
| Light | Vacuum | 3 × 10⁸ m/s |
| Light | Glass | ~2 × 10⁸ m/s |
| Seismic P-wave | Earth's crust | 5000–8000 m/s |
| Seismic S-wave | Earth's crust | 3000–4500 m/s |
Worked Example
You hear thunder 4.5 seconds after seeing lightning. How far away is the storm?
Using v = 343 m/s for sound in air:
d = v × t = 343 × 4.5 = 1543.5 m ≈ 1.5 km
The old "5 seconds = 1 mile" rule is a rough approximation of this calculation (1 mile ≈ 1.6 km, and 5 × 343 = 1715 m).
Why does sound travel faster in warm air?
Temperature affects molecular speeds. Warmer air molecules move faster and collide more frequently, transmitting pressure waves more quickly. Speed of sound in air: v ≈ 331 + 0.6T m/s, where T is in Celsius. At 0°C it's 331 m/s; at 20°C it's 343 m/s.
Do all waves travel at the same speed?
No. Only electromagnetic waves in a vacuum all travel at c = 3 × 10⁸ m/s. Sound, water, and seismic waves depend entirely on the properties of their medium. Faster medium = higher wave speed, with frequency or wavelength adjusting accordingly.
What's the difference between transverse and longitudinal waves?
Longitudinal waves oscillate parallel to their direction of travel (sound, seismic P-waves). Transverse waves oscillate perpendicular (light, water surface waves, seismic S-waves). Both follow v = fλ, but transverse waves can be polarized; longitudinal waves cannot.