Calculate the RT60 decay time for your home theater. Optimize your room's acoustics for clear dialogue and tight bass by managing sound reflections. Achieving the correct reverberation time ensures that your audio system sounds detailed and immersive without being muddy or overly dry.
The RT60 Reverberation Time Calculator applies the Sabine equation T60 = 0.161 × V / A to predict how long sound takes to decay 60 dB in your room. Excessive reverberation smears dialogue and bloats bass, while an over-damped room sounds lifeless. Most home theaters target 0.3–0.5 seconds, the range validated by dialogue intelligibility research and aligned with cinema mixing stages.
Enter your room's length, width, and height in meters to compute total volume V in cubic meters. For each surface (walls, floor, ceiling, doors, carpet, drapes), supply the area in square meters and the material's NRC absorption coefficient (0.00 reflective to 1.00 fully absorptive). The calculator sums every surface as area × NRC to derive total absorption A in sabins, then returns T60 = 0.161V/A in seconds.
Enter your room dimensions (width, length, height) and select the surface material for each of the 6 surfaces. The calculator uses the Sabine formula: RT60 = 0.161 × V / A, where V is room volume in m³ and A is total absorption in m².
The ideal RT60 for a home theater is 0.3–0.5 seconds. Rooms with mostly hard surfaces (concrete, tile, glass) have high RT60. Soft surfaces (carpet, curtains, acoustic panels) reduce RT60.
NRC (Noise Reduction Coefficient) values range from 0.0 (perfect reflector) to 1.0 (perfect absorber). Carpet has NRC ~0.40, while acoustic panels rate 0.70–0.95. Professional acoustic foam can achieve NRC 0.80–0.90.
0.3–0.5 seconds across 250–4000 Hz, based on dialogue intelligibility studies and the same range used in professional film dubbing stages. Below 0.2 s the room sounds dead and fatiguing; above 0.6 s consonants smear and surround effects lose their spatial cues.
The Sabine formula T60 = 0.161 × V / A (metric) assumes a diffuse sound field and works well when average absorption is below about 0.30. For heavily treated rooms with average absorption above 0.30, the Eyring correction is more accurate because Sabine overestimates reverberation in dead rooms.
Painted drywall NRC ≈ 0.05, glass window 0.05, carpet on concrete 0.25–0.35, heavy velour drape 0.55, 2-inch fiberglass panel 0.80–0.95, and an empty room couch around 0.40. Always use the manufacturer's third-party tested NRC rating rather than marketing claims.
Yes. Sabine's formula calculates broadband reverb, but real rooms have very different decay times at 125 Hz versus 4 kHz. Most porous absorbers like fiberglass are weak below 250 Hz, which is why bass traps and Helmholtz resonators are needed to control low-frequency RT60 in dedicated theaters.
Yes — use free software like Room EQ Wizard (REW) with a calibrated USB microphone. Play a swept sine wave or impulse, then read the T20 or T30 decay (extrapolated to 60 dB). Real measurements typically fall within ±15% of Sabine predictions for untreated rooms.