Acoustic Treatment Calculator
How much absorptive treatment a room needs to reach a target reverberation time — from its volume, its current reverberation and the absorption coefficient of the panels you plan to add.
Sabine’s equation links reverberation time to room volume and total absorption: RT = 0.
How the acoustic treatment calculator works
Sabine’s equation links reverberation time to room volume and total absorption: RT = 0.161 V ÷ A. A room’s existing absorption follows from its current RT; the absorption for the target RT follows the same way; the difference is what the panels must add, and dividing by their absorption coefficient gives the area to install. Speech needs RT around 0.5–0.8 s in small rooms; music rooms and churches more.
Formula: A = 0.161 V ÷ RT; panel area = (A_target − A_now) ÷ α_panel
Worked examples
| Inputs | Panel area to add | Note |
|---|---|---|
| 8 × 6 × 3 m room from 1.4 s to 0.6 s with α 0.85 | 26 m² | 26.0 m² — about 37 panels |
| A 300 m³ hall from 2.2 s to 1.2 s with ceiling tile α 0.6 | 30.5 m² | 30.5 m² |
| Already dry enough | 0 m² | none needed |
FAQFrequently asked questions
How do I measure the current reverberation time?
Clap or burst a balloon and record it, then read RT60 from the decay in a free app or audio editor; or estimate it from the finishes with the reverberation time calculator. Measure at mid frequencies (500 Hz–1 kHz).
What target should I aim for?
About 0.4–0.6 s for a home studio or meeting room, 0.6–0.8 s for a classroom or restaurant, 1.0–1.5 s for a music rehearsal room, 1.5–2.5 s for a concert hall. Longer than 1 s makes speech hard to follow.
Where should the panels go?
Spread across walls and ceiling rather than clustered, at the first reflection points for speech and at the rear wall to stop echoes; corners for bass traps. Panels on one wall alone leave flutter between the others.
Why do coefficients vary with frequency?
Thin absorbers work only at high frequencies; 50 mm of mineral wool absorbs well above about 250 Hz, 100 mm above 125 Hz. The calculator uses one mid-frequency figure; bass needs thicker or resonant absorbers.
Where these figures come from
- Sabine (1922) — Collected Papers on Acoustics — the reverberation-time equation
- CIBSE Guide A — Environmental design — daylight, comfort and ventilation criteria
- Neufert — Architects' Data — the standard reference for space and dimension
- International Code Council — International Building Code — occupant load and egress factors
- Australian Building Codes Board — National Construction Code — the body that writes Australia's building code
Last checked: September 2026. Formulas are the standard building-science and code relationships; default thresholds are common international values and should be replaced with the ones in your code.