Room Mode Calculator
Estimate the fundamental axial room modes — the standing waves that form between each pair of parallel walls in a room. These low-frequency resonances are the main cause of boomy or uneven bass in small rooms and studios.
Enter Values
How to use this calculator
- Enter the room's length, width and height in metres.
- Read off the fundamental (n=1) axial mode for each dimension in hertz.
- Note that each mode repeats at 2× and 3× its fundamental as harmonics — clusters of these frequencies are where bass problems concentrate.
How it works
An axial mode is a standing wave bouncing between two parallel surfaces. Its fundamental frequency is the speed of sound (343 m/s in air at about 20 °C) divided by twice the distance between the walls: f = c ÷ (2 × L). Higher-order axial modes sit at whole-number multiples (2×, 3×, …) of this fundamental. Longer dimensions give lower modes, which is why room length usually sets the lowest resonance.
Worked example
Worked example. A room 5 m long, 4 m wide and 2.7 m high gives a length mode of 343 ÷ (2 × 5) = 34.3 Hz, a width mode of 42.875 Hz and a height mode of 63.519 Hz. The length mode also resonates at 68.6 Hz and 102.9 Hz.
Common mistakes
- Only checking one dimension — every pair of parallel walls has its own mode series, and they interact.
- Ignoring harmonics: the 2nd and 3rd multiples of each fundamental are also strong and often overlap between dimensions.
- Assuming these numbers describe the whole room — tangential and oblique modes, furnishings and treatment all shift the real response.
Frequently asked questions
Why are axial modes the most important?
They involve only one pair of surfaces, so they carry the most energy and produce the loudest peaks and dips. Tangential (four surfaces) and oblique (six surfaces) modes are weaker.
How do I reduce room mode problems?
Choose non-square room proportions, position the listener and speakers away from mode peaks, and add bass trapping in corners where low-frequency pressure is highest.
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- Room Absorption (Sabine) Calculator
- Frequency & Wavelength Calculator
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