What Is a Room Reverberation Time (RT60) Calculator?
RT60 is the standard measurement of how "live" or "dead" a room sounds — the time it takes reverberant sound to decay by 60 decibels after the source stops. This calculator estimates RT60 from your room's volume and an average absorption coefficient for its surfaces, using the classic Sabine formula developed by physicist Wallace Sabine, the founder of modern architectural acoustics.
Recording studios, home theaters, classrooms and concert halls all target specific RT60 ranges depending on their purpose, and this calculator gives a fast first estimate before investing in acoustic treatment.
How to Read Your Results
Estimated RT60
The predicted reverberation time in seconds. Small, well-treated rooms (like vocal booths) often aim for under 0.4s; living rooms and offices typically land between 0.4-0.8s; larger untreated spaces can run well over 1s.
Room Volume
The total air volume of the room in cubic meters, calculated from length × width × height. Larger volumes generally increase RT60 unless absorption also increases proportionally.
Total Surface Area
The combined area of all four walls, the floor and the ceiling, in square meters.
Total Absorption
Surface area multiplied by your average absorption coefficient, measured in "sabins" — the unit of total sound absorption named after Wallace Sabine.
Real-World Example
A 5m × 4m × 2.7m living room (volume 54 m³) with different amounts of soft furnishing:
| Room condition | Avg. absorption | RT60 |
|---|---|---|
| Bare walls, hard floor | 0.10 | ≈0.94 s |
| Rug, curtains, sofa | 0.20 | ≈0.47 s |
| Heavy carpet + acoustic panels | 0.35 | ≈0.27 s |
Doubling the average absorption coefficient roughly halves RT60 — adding soft furnishings and acoustic panels is the fastest way to tame an echoey room.
Tips for Managing Room Acoustics
- Speech clarity favors shorter RT60, typically under 0.6s for classrooms and offices.
- Music performance spaces often want longer RT60, sometimes 1.5-2s in concert halls, for a fuller sound.
- Soft, porous materials (rugs, curtains, acoustic foam, upholstered furniture) absorb far more sound than hard, flat surfaces.
- Corners and parallel walls cause specific echo and standing-wave problems that an average-coefficient estimate like this one won't capture.
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Last updated: August 2026 · Reviewed by: Simple Calculator Tools Editorial Team