Room Reverb Time Calculator — RT60, Early Reflections & Optimal Reverb Setting

A home studio control room should aim for an RT60 of 0.3–0.6 seconds across mid frequencies. Too short (below 0.2s) and the room sounds unpleasantly dead. Too long (above 0.8s) and the room's reverb masks detail in recordings and mixes. A vocal booth should be even drier: 0.15–0.3s.

Hard, non-porous surfaces (concrete, tiles, glass) reflect most sound energy, giving a long RT60. Soft, porous materials (carpet, curtains, acoustic foam) absorb energy and shorten RT60. A bare concrete room might have an RT60 of 2–4 seconds; the same room with carpet and curtains could fall to 0.6–1.0 seconds.

Early reflections are the first discrete echoes that arrive within roughly 80ms of the direct sound. They contribute to the sense of room size and can cause comb filtering at a listening position. Reverb is the dense buildup of reflections that follow, characterised by the RT60. In a mix, pre-delay on a reverb plugin simulates the gap between the dry signal and the onset of reverb.

Pre-delay separates the dry signal from the reverb tail, preserving intelligibility especially on vocals. This calculator estimates a starting pre-delay from the one-way travel time from the source to the nearest wall (the path a first reflection adds before it returns). In a small room this lands at a few milliseconds; many engineers then push it higher — 20–40ms is common on vocals — to open up clarity. Use the early reflection delay value from this calculator as the upper reference point.

The calculator shows how many additional sabins of absorption are needed to reach the ideal RT60. Each square metre of acoustic panel with an absorption coefficient of 0.85 provides roughly 0.85 sabins. So if you need 10 extra sabins, around 12m² of treatment is needed. Bass traps in corners are especially effective for low frequencies.