Example 1
At 440 Hz and 343 m/s the wavelength is 0.7795 m, or 77.95 cm. The period is 2.2727 ms, and the feet line is 2.5576 ft.
Sound Wavelength Calculator
Enter a frequency in hertz. The calculator finds wavelength with λ = v ÷ f. When the speed field is empty, it uses 343 m/s (air near 20 °C). At 440 Hz the result is 0.7795 m, or 77.95 cm; the period is about 2.27 ms. This is a sound wave, not an electromagnetic wavelength that uses the speed of light.
Result
Enter a frequency. The result shows up here.
Note Hz: frequency from A4. Transposition: new hertz. Quotient: f2/f1. Wave physics: wavelength.
How it works
v343 m/s
f440 Hz
λ0.7795 m
Wavelength is the distance sound travels in one period. The formula is λ = v / f. In air near 20 °C the calculator uses 343 m/s when the speed field is left empty. At A4 = 440 Hz the result is 343 / 440 = 0.7795 m, or 77.95 cm, and the period T = 1/f is 2.2727 ms. In feet that is 2.5576 ft, because meters are divided by 0.3048. One octave higher, at 880 Hz, the wave is 0.3898 m. Two waves fit the same path because the frequency doubled.
At 20 Hz, near the lower edge of hearing, the wave is 17.1500 m and the period is 50.0000 ms. At 100 Hz the wave is 3.4300 m. At 1000 Hz the wave is 0.3430 m, or 34.30 cm, and the period is 1.0000 ms. At 2000 Hz the wave is 0.1715 m. When frequency equals speed, here 343 Hz and 343 m/s, λ = 1.0000 m. C4 entered as 261.63 Hz gives 1.3110 m.
If you leave the speed empty, the calculator fills in 343 m/s. An entered value overwrites that default: 1480 m/s is about the speed of sound in fresh water, and 5100 m/s is common in steel. An entered zero for speed does not pass, because wavelength needs a positive speed. Frequency must be positive too, because zero has no period and no wavelength.
The calculator finds feet as meters divided by 0.3048. The speed field stays in meters per second even when the header is set to US. Do not convert the speed to ft/s in that field. The feet result still appears beside the meters as one line.
Enter the frequency, and the speed if you need a value other than 343 m/s, then click Calculate. A comma in 261.63 works the same way as a period. This calculator is for sound, not for an arbitrary electromagnetic wave. The general formula λ = v / f without a 343 m/s default is on the physics wavelength page. Intensity in decibels is a separate page. Note hertz, transposition, and the quotient of two frequencies have their own calculators.
In a small room a 17 m wave at 20 Hz does not fit, which is why low bass is uneven. At 343 Hz the wavelength is one meter and microphone spacing is easier to set. Centimeters and the period do not have their own fields, because they come from the same two numbers. The drawing shows one cycle of the wave along a short axis and labels it with the computed length.
How to use
- Enter the frequency in Hz, for example 440. You may leave the speed empty: the calculator then fills in 343 m/s.
- If you are working in water or steel, enter your own speed in m/s. The US header will not convert it to ft/s.
- Click Calculate or choose a button. 440 Hz and 343 m/s give 0.7795 m, 77.95 cm, a period of 2.2727 ms, and 2.5576 ft.
- 20 Hz and 343 m/s give 17.1500 m. 1000 Hz and 343 m/s give 0.3430 m.
- For note hertz from A4, open the note-frequency calculator. For a wave that is not sound, open wavelength in physics, which does not default to 343 m/s.
Formula
λ = v / f
T = 1 / f
centimeters = λ × 100
feet = λ / 0.3048
Frequency and speed must be greater than zero. An empty speed field means 343 m/s. The speed field stays in m/s regardless of the US header.
The relation λ = v / f is the ordinary wave formula, because v = fλ, and it has no single author. 343 m/s is the accepted speed of sound in air near 20 °C, not a result from a separate temperature field.
The calculator does not find note hertz, transposition, or the quotient of two frequencies.
Hz, speed, and wavelength in air
Here λ = v / f. At 440 Hz and 343 m/s the wave is 0.7795 m, or 77.95 cm. The period is 2.2727 ms. An empty speed field inserts 343 m/s.
- Hz
- Frequency f in hertz. 440 at 343 m/s gives 0.7795 m. A higher frequency shortens the wave. This is not a note transposition.
- m/s
- Sound speed in the v field. An empty field is 343 m/s, air near 20 °C. An entered 1480 m/s is about the speed of sound in fresh water and does not give the 0.7795 m from A4.
- λ
- Wavelength in meters, which is v / f. At 440 Hz and 343 m/s it is 0.7795 m.
- T
- The period, which is 1/f. At 440 Hz it is 2.2727 ms. There is no separate field for it.
- cm
- The same meters multiplied by 100. At 440 Hz that is 77.95 cm.
Real-life examples
Example 2
At 20 Hz and 343 m/s the wave is 17.1500 m, and the period is 50.0000 ms.
Example 3
At 1000 Hz and 343 m/s the wave is 0.3430 m, or 34.30 cm. The period is 1.0000 ms.
Example 4
At 261.63 Hz and 343 m/s the C4 wave is 1.3110 m.
Example 5
At 880 Hz and 343 m/s the wave is 0.3898 m, which is half the 440 Hz result.
Example 6
At 100 Hz and 343 m/s the wave is 3.4300 m.
Example 7
At 343 Hz and 343 m/s the wave is 1.0000 m, because the frequency equals the speed.
Example 8
At 2000 Hz and 343 m/s the wave is 0.1715 m.
Ways to use this calculator
- You check whether a bass wave at a known Hz fits the room before you place a subwoofer.
- You compare a note wavelength with microphone spacing when you want to avoid a hole in the range you are recording.
- You check 440 Hz and 343 m/s: 0.7795 m, 77.95 cm, and a period of 2.2727 ms should come back every time.
Frequently asked questions
How does the calculator find the wavelength?
The calculator divides the speed of sound by the frequency: λ = v / f. At 440 Hz and 343 m/s the result is 0.7795 m, or 77.95 cm. The period T = 1/f is 2.2727 ms, and the feet line is 2.5576 ft. At 880 Hz and the same speed the wave is 0.3898 m, which is half.
What happens when the speed field is left empty?
The calculator fills in 343 m/s. That is a typical speed of sound in air near 20 °C. An entered 1480 m/s overwrites that value. That figure is about the speed of sound in fresh water.
Where do centimeters and the period come from if the form has two fields?
Centimeters are the wavelength times 100, and the period is 1/f. Both come from the frequency and the speed. At 1000 Hz and 343 m/s the wave is 0.3430 m, or 34.30 cm, and the period is 1.0000 ms. At 20 Hz the wave is 17.1500 m and the period is 50.0000 ms. At 100 Hz the wave is 3.4300 m.
Does the US header convert the speed field to feet per second?
No. The speed field stays in m/s. Feet are one result line: meters divided by 0.3048. At 440 Hz and 343 m/s that line is 2.5576 ft.
When is the result exactly 1.0000 m?
When the frequency in hertz equals the speed in meters per second. At 343 Hz and 343 m/s the calculator shows 1.0000 m.
Is this the same calculator as wavelength in physics?
The formula is the same: λ = v / f. Here an empty speed field means 343 m/s, and a feet line sits beside the meters, because this page is about sound. The physics calculator does not fill in air.
Where do I get note hertz, transposition, or a frequency quotient?
Note hertz come from the frequency calculator that starts at A4. At C4, which is 261.63 Hz, and 343 m/s the wave is 1.3110 m. Transposition and the quotient f2/f1 have their own pages. This calculator does not repeat them.
What does the drawing next to the result show?
The drawing shows one cycle of the wave along a short axis and labels it with the computed length. At 2000 Hz and 343 m/s that length is 0.1715 m. The axis is not a floor plan.
How do I calculate sound wavelength with λ = v/f?
Divide the speed of sound by frequency in hertz. At 343 m/s and 440 Hz: 343 ÷ 440 ≈ 0.7795 m (77.95 cm).
How many meters is a 440 Hz wave in air at 20 °C?
About 0.7795 m when v = 343 m/s. The period is 1000 ÷ 440 ≈ 2.2727 ms. The main result and the extra fields show those same numbers.
What is the wavelength at 1000 Hz and 343 m/s?
343 ÷ 1000 = 0.343 m, or 34.3 cm. The period is 1 ms.
Why is the default speed 343 m/s instead of 340?
343 m/s is a common air estimate near 20 °C. If a problem states 340 m/s or water, enter that speed in the speed field.
Does wavelength change when sound enters water?
Yes, because v changes while the source frequency stays. Higher v at the same f means a longer wave. Enter the water speed when you know it.
How do I get wavelength from a note’s hertz?
First find hertz on the note frequency page (for example A4 = 440 Hz), then enter those hertz here. The note page does not compute λ itself.
Knowledge sources
Sound wavelength follows the relation λ = v / f. The speed 343 m/s is the usual value for air near 20 °C. The 440 Hz example follows the A440 pitch standard.
Page updated November 3, 2026.