How the room mode calculator works
Sound bouncing between two parallel walls reinforces itself at frequencies whose half-wavelength fits the distance exactly. These standing waves, called axial modes, cause boomy peaks and dead spots in the bass.
c ≈ 1,130 ft/s (speed of sound at about 70 °F)
Schroeder frequency ≈ 2,000 × √(RT60 ÷ Volume in m³)
Axial modes are the strongest; tangential and oblique modes involve four or six surfaces and are weaker. Below the Schroeder frequency, individual modes dominate the sound; above it, the room behaves more evenly. When modes from different dimensions land close together, they stack into a strong peak, which is why cube-shaped rooms and dimensions that are multiples of each other sound worst.
Worked example
A 20 × 15 × 8 ft room has a first length mode at 1,130 ÷ 40 = 28.3 Hz, then 56.5, 84.8 and 113 Hz. Width modes start at 37.7 Hz and height modes at 70.6 Hz. The second width mode (75.3 Hz) and first height mode (70.6 Hz) are close together, so expect a buildup in the low 70s.
Frequently asked questions
What are room modes?
Resonant frequencies at which sound waves reinforce between room surfaces, causing uneven bass.
What are the best room proportions?
Ratios that spread modes evenly, such as those studied by Bolt and Louden. Avoid equal or doubled dimensions.
Can EQ fix room modes?
EQ can reduce peaks at the listening position but cannot fill deep nulls. Placement and bass trapping work better.
Do I enter dimensions in feet?
Yes. To convert metres, multiply by 3.281.
Updated October 2026. Results are estimates for education, not financial or medical advice. All math runs in your browser; nothing you type is sent anywhere.