Reverberation Time (RT60) Calculator

About this calculator

RT60 is the time it takes for sound in a room to decay by 60 decibels after the source stops — the standard measure of how “live” or “dead” a space sounds. The classic estimate is Sabine’s formula, RT60 = 0.161 × V / A (metric units), where V is the room’s volume in cubic meters and A is the total sound absorption in sabins, calculated by summing each surface’s area times its absorption coefficient α (Σ Sᵢαᵢ) across floor, walls, ceiling, and furnishings.

Architectural acousticians use RT60 as a primary design target: concert halls typically aim for 1.8-2.2 seconds to give orchestral music warmth and blend, recording studios and voice-over booths aim much shorter (under 0.5s) for clarity and to avoid muddying dialogue, and classrooms are designed for short RT60 specifically because excessive reverberation degrades speech intelligibility for students. Enter a room’s volume, total surface area, and average absorption coefficient, and this calculator applies Sabine’s formula to estimate RT60.