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Wavelength Calculator
Convert between frequency and wavelength for sound waves, electromagnetic waves, and radio frequencies. Enter either value for instant bidirectional conversion.
Wave Parameters
Wave Speed:
343 m/s
Result
Wavelength
0.3432
meters
cm
34.32
mm
343.2
inches
13.51
feet
1.126
Formula
λ = v / f
λ = 343 / 1000 = 0.343 m
Audio Frequency Wavelength Reference (Sound in Air at 20°C)
| Frequency | Wavelength (m) | Wavelength (cm) | Notes |
|---|---|---|---|
| 20 Hz | 17.16 m | 1716 cm | Lowest audible bass |
| 40 Hz | 8.58 m | 858 cm | Sub-bass |
| 80 Hz | 4.29 m | 429 cm | Bass |
| 100 Hz | 3.43 m | 343 cm | Bass/room mode range |
| 440 Hz | 0.780 m | 78.0 cm | Concert A (440 Hz) |
| 1 kHz | 0.343 m | 34.3 cm | Mid-range reference |
| 4 kHz | 0.0858 m | 8.58 cm | Presence/attack range |
| 10 kHz | 0.0343 m | 3.43 cm | High treble |
| 20 kHz | 0.01716 m | 1.72 cm | Upper hearing limit |
Understanding Wavelength and Frequency
Wavelength (λ) and frequency (f) are inversely related through wave speed (v): λ = v / f. Double the frequency and the wavelength halves. This relationship is fundamental to acoustics, optics, and radio engineering.
Why Wavelength Matters in Audio
- Room acoustics — standing waves (room modes) occur when the room dimension equals a half-wavelength (or multiple). A 17 m room has a 20 Hz mode.
- Speaker placement — bass management, subwoofer placement, and boundary effects all depend on wavelength relative to room dimensions.
- Microphone design — microphone diaphragms should be small relative to the shortest wavelength to avoid interference.
- Acoustic treatment — bass traps must be physically thick relative to wavelength: λ/4 depth for a quarter-wave absorber at target frequency.
Wavelength vs. Wave Type
The formula λ = v/f applies to all waves, but wave speed varies dramatically:
- Sound in air: ~343 m/s → 1 kHz has λ = 0.343 m
- Sound in water: ~1481 m/s → 1 kHz has λ = 1.481 m
- Light in vacuum: 3×10⁸ m/s → 500 THz (visible green) has λ = 600 nm
- FM radio in air: ~3×10⁸ m/s → 100 MHz has λ = 3 m
Frequently Asked Questions
What is the wavelength of 440 Hz (concert A)?
At 20°C in air, the wavelength of concert A (440 Hz) is 343.2 / 440 = 0.780 m (78.0 cm or 30.7 inches). In a violin string, the same 440 Hz corresponds to a half-wavelength equal to the string length when it vibrates in its fundamental mode.
How do I convert wavelength to frequency?
Frequency (f) = wave speed (v) ÷ wavelength (λ). For sound in air: f = 343 / λ. For a 1-meter wavelength: f = 343 / 1 = 343 Hz. Switch to Wavelength → Frequency mode above and enter your wavelength value.
What is the wavelength of FM radio waves?
FM radio broadcasts between 87.5–108 MHz. Using λ = c/f with c = 3×10⁸ m/s: at 100 MHz, λ = 3×10⁸ / 10⁸ = 3 meters. This is why FM antennas are roughly 75 cm long (quarter-wavelength dipole).
Why are bass frequencies harder to absorb acoustically?
Low frequencies have long wavelengths. A 100 Hz wave has λ = 3.43 m. Effective absorption requires material thickness of at least λ/4 ≈ 86 cm. That's why effective bass traps are physically large — thin foam panels only work for shorter wavelengths (higher frequencies).