Sabine equationSingle-number estimate

Estimate RT60

Enter a room volume and a separately established equivalent absorption area. The result is a bounded diffuse-field estimate—not a target, measurement, or compliance check.

Who it's for: acoustical consultants and architects estimating reverberation time at design development from an already established absorption area.

How to use this calculator

Establish room volume

Use the enclosed acoustic volume in cubic metres.

Establish equivalent absorption area

At one declared frequency band, sum each verified surface area multiplied by its applicable absorption coefficient.

Calculate the estimate

The tool returns 0.161 times volume divided by equivalent absorption area.

Evaluate applicability

Check diffusion, geometry, absorption distribution, frequency range, air absorption, coupled spaces, and the project acoustic brief separately.

The formula

RT60 = 0.161 × V ÷ A, where V is room volume in m³ and A is equivalent absorption area in m² sabins.

Worked example

Example

For V = 240 m³ and A = 83.5 m² sabins, RT60 = 0.161 × 240 ÷ 83.5 = 0.463 seconds.

When this estimate will be off

Assumes a sufficiently diffuse sound field and uniformly effective absorption; irregular, highly absorptive, coupled, or poorly diffused rooms can require another method or simulation.
Returns one estimate from one absorption-area input. It does not calculate octave-band coefficients, source material data, air absorption, background noise, speech intelligibility, or decay from measurements.
No generic classroom, office, healthcare, performance, or certification target is applied. Select targets from the applicable editioned standard and project brief.
ISO 3382 measurement is a separate field procedure; this arithmetic does not predict that a constructed room will meet a measured criterion.

Frequently asked questions

What is the most common mistake?

A common mistake: Assumes a sufficiently diffuse sound field and uniformly effective absorption; irregular, highly absorptive, coupled, or poorly diffused rooms can require another method or simulation.

Why are material presets gone?

The former page embedded unsourced single-frequency coefficients. This version requires the user to establish equivalent absorption area from project-appropriate, frequency-consistent data.

Does this pass or fail a room?

No. Appropriate targets depend on the project, space, volume, frequency bands, jurisdiction, and editioned acoustic criteria.

Sources

NIST — The Measurement of Sound Absorption — Historical primary technical source describing Sabine reverberation-time theory and its limitations in highly absorptive rooms
ISO 3382-2:2008 — Current confirmed standard for reverberation-time measurement in ordinary rooms; not implemented as a measurement procedure here

Sources and review record

Sources and method basis

NIST Journal of Research: The Measurement of Sound Absorption (Sabine theory and limitations)
ISO 3382-2:2008 (confirmed 2022) measurement context only
https://www.nist.gov/
https://www.iso.org/standards.html

Limitations

Single-number diffuse-field estimate only; frequency bands, coefficient selection, geometry, nonuniform absorption, coupled spaces, air absorption, measurement, targets, and compliance are excluded.

This free Sabine RT60 Calculator is built and maintained by DataDrivenAEC, using the relevant codes and standards. It does not substitute for professional judgment.

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