Tool

Room mode calculator

Every rectangular room boosts some bass notes and starves others. Here are yours.

Home Theater Guides Updated Oct 4, 2026 4 sources

Lengthft Widthft Ceiling heightft Up to: 200 Hz

Lowest room mode

35.2 Hz

64 modes below 200 Hz: 11 axial, 32 tangential, 21 oblique. Above roughly 184 Hz (the Schroeder frequency, assuming a 0.4 s decay) modes overlap enough that individual ones matter less.

Axial Tangential Oblique (bar heights follow the textbook −3/−6 dB convention, a rough guide only)

Axial modes within 5% of each other at 70 Hz, 141 Hz, 176 Hz: those notes tend to boom. Rooms whose dimensions are multiples of each other stack modes like this.

Mode	Type	Frequency	Note
(1,0,0) · length	axial	35.2 Hz	C♯1
(0,1,0) · width	axial	43.3 Hz	F1
(0,0,1) · height	axial	70.3 Hz	C♯2
(2,0,0) · length	axial	70.3 Hz	C♯2
(0,2,0) · width	axial	86.6 Hz	F2
(3,0,0) · length	axial	105.5 Hz	G♯2
(0,3,0) · width	axial	129.8 Hz	C3
(0,0,2) · height	axial	140.7 Hz	C♯3
(4,0,0) · length	axial	140.7 Hz	C♯3
(0,4,0) · width	axial	173.1 Hz	F3
(5,0,0) · length	axial	175.8 Hz	F3

How it works

For a rectangular room with hard walls, the mode frequencies follow one formula: f = (c ÷ 2) × √((nx ÷ L)² + (ny ÷ W)² + (nz ÷ H)²), with c the speed of sound (343 m/s) and n whole numbers. Modes with one non-zero number run along one dimension (axial), two (tangential) or all three (oblique).

Axial modes are usually the strongest, which is why the chart draws them tallest. The often-quoted −3 dB for tangential and −6 dB for oblique modes is a textbook convention (Everest and Pohlmann) rather than a law: wall construction and the source and listener positions change the real levels.

This calculator lists frequencies. It doesn’t predict how loud each one will be at your seat; for that, use the subwoofer placement simulator, which adds up every mode for a given sub and seat.

Questions people ask

What are room modes?

Standing waves between a room’s surfaces at frequencies where whole numbers of half-wavelengths fit between them. At those frequencies bass builds up near the walls and cancels at points in between, so some notes boom and others vanish depending on where you sit.

What is the Schroeder frequency?

A rough estimate of where individual modes stop dominating because they overlap: 2000 × √(decay time ÷ volume). In a typical living room it falls somewhere around 100–200 Hz. It is a transition, not a sharp boundary.

Can I fix room modes?

Partly. Moving the seat and the subwoofer changes which modes you hear most; two or more subs even out the response across seats; thick bass traps and room EQ reduce the worst peaks. Deep dips can’t be fixed with EQ, only by moving things.