Open Pipe Resonance Calculator

About this calculator

An open pipe (open at both ends) resonates when it fits a whole number of half-wavelengths, giving harmonic frequencies f = n·v/(2L), where n = 1, 2, 3... is the harmonic number, v is the speed of sound (≈343 m/s in air at 20°C), and L is the pipe length. Unlike a closed pipe, which only supports odd harmonics, an open pipe supports every integer harmonic, which is why its tone sounds fuller and brighter.

Musical-instrument makers and acousticians use this relationship to design and tune open flue pipes in organs, flutes, and open-ended resonance tubes, since it directly determines the pitch produced for a given pipe length and lets a builder work backward from a target note to the required length.