Port Length Calculator
Calculate the required port length for a vented (bass reflex) enclosure. Enter your box volume, desired tuning frequency, and port diameter to determine the correct length.
Hz
Formula
The port length is calculated using the standard Helmholz resonator equation:
Lv = (Av × c²) / (Vb × fb² × π²) - (0.732 × √Av) Where:
- Lv = Port length (meters)
- Av = Port cross-sectional area (m²)
- c = Speed of sound (~343 m/s)
- Vb = Box volume (m³)
- fb = Tuning frequency (Hz)
The end correction factor accounts for radiation impedance at the port opening.