Frequência Tubo Fechado
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
tubo fechado
About this calculator
The closed tube frequency calculator determines the fundamental frequency of a sound tube with one closed end and one open end. It is based on the formula f = v / (4L), where v is the speed of sound in the medium (usually 343 m/s in air at 20°C) and L is the tube length. This relationship arises because, in a closed tube, the fundamental wavelength is four times the tube length, as a node forms at the closed end and an antinode at the open end.
To use the calculator, input the speed of sound and the tube length. The result is the fundamental frequency in hertz (Hz). It can also calculate odd harmonics, since closed tubes only produce odd harmonics (1st, 3rd, 5th...). This tool is useful for musicians building instruments like panpipes, clarinets, or organs, as well as for physics students studying standing waves.
Use cases include designing wind musical instruments, adjusting room resonance for concerts, and educational experiments in acoustics. It is important to note that the speed of sound varies with temperature and humidity, and that very narrow or wide diameters may cause end corrections, changing the effective tube length. The calculator provides an idealized theoretical value.
Frequently asked questions
Why do closed tubes only produce odd harmonics?
In a closed tube, the closed end is a displacement node and the open end is an antinode. This forces the fundamental wavelength to be 4L, and possible harmonics are odd multiples of the fundamental, since an even harmonic would require a node at the open end, which does not occur.
How does temperature affect the frequency calculation?
The speed of sound increases with temperature (about 0.6 m/s per °C). If you use the calculator at a temperature different from 20°C, adjust the speed of sound value for a more accurate result.
Does the tube diameter influence the frequency?
Yes, for very narrow or wide tubes, the effective length may differ slightly from the geometric length due to end corrections. The calculator assumes an ideal tube without corrections.
Is this calculator suitable for instruments like the recorder?
The recorder is an open tube at both ends, so the correct formula is f = v/(2L). For closed tubes, think of instruments like the clarinet or panpipes with one closed end.
What unit of length should I use?
Use meters (m) to get frequency in hertz. If you input length in centimeters, convert to meters by dividing by 100 before using the calculator.