Sabine Reverberation Time Calculator

Enter the room volume in cubic metres and its total equivalent absorption area in metric sabins. The calculator applies the standard metric form of the Sabine equation, RT60 = 0.161 × V ÷ A, and returns a deterministic result suitable for early acoustic design, treatment comparisons, classroom exercises, and repeatable API workflows.

What the Sabine result represents

Reverberation time, commonly written as RT60, describes the time required for a diffuse sound field to fall by 60 decibels after its source stops. A longer result suggests that sound energy remains in the room for more time, while a shorter result suggests that surfaces and furnishings remove energy more quickly. This calculator uses the metric Sabine equation: RT60 = 0.161 × V ÷ A. In that expression, V is the enclosed room volume in cubic metres and A is the total equivalent absorption area in metric sabins, where one metric sabin is equivalent to one square metre of perfectly absorbing area. The result is expressed in seconds. Sabine reverberation time is most useful as a broad, first-order estimate for rooms whose sound field is reasonably diffuse and whose absorption is not extremely high. It does not describe every reflection, echo, resonance, or seat-to-seat variation. Treat the calculated value as an acoustical design indicator that helps compare scenarios consistently, rather than as a substitute for measurements or a detailed simulation of a complex space.

Preparing volume and absorption inputs

Calculate room volume in cubic metres before using the tool. For a rectangular room, multiply internal length, width, and height; for irregular spaces, divide the geometry into simpler solids and add their volumes. Total absorption requires a different calculation. Multiply the area of each material by its absorption coefficient at the frequency of interest, then add the contributions from all surfaces, furnishings, occupants, and other absorbers. The resulting sum is entered as total_absorption_sabins. Absorption coefficients vary with frequency, so a single room can have different reverberation times in different octave bands. For meaningful comparisons, use coefficients from the same frequency band and under comparable mounting conditions. Both inputs must be finite numbers greater than zero. Do not enter dimensions in feet, volume in cubic feet, or absorption in imperial sabins: the constant used here is specifically the metric value 0.161. Also avoid entering an average absorption coefficient by itself. The equation needs total equivalent absorption area, not a dimensionless average, unless you first multiply that average by the room's total surface area.

Interpreting and applying the estimate

Use the result to compare design alternatives under a consistent set of assumptions. For example, keep room volume fixed and increase total absorption to estimate the effect of adding ceiling panels, curtains, seating, or other treatment. Because absorption appears in the denominator, doubling the total metric sabins halves the estimated reverberation time. Likewise, keeping absorption fixed while doubling volume doubles the estimate. These relationships make the calculator useful for quick sensitivity checks and for documenting why one treatment package is expected to outperform another. However, a target RT60 depends on room use, size, occupancy, and frequency; speech rooms, music venues, studios, and industrial spaces do not share one universal ideal. Sabine's model also assumes sufficiently mixed sound energy and evenly effective absorption. Strongly localized treatment, unusual geometry, coupled rooms, flutter echoes, and very absorptive spaces can make other models or direct measurements more appropriate. When decisions affect construction, safety, compliance, or substantial cost, confirm the estimate with band-specific analysis and qualified acoustic advice. The API price is $0.002 per request, while the same deterministic calculation can run locally in the browser.