RT60 (also written T60) is the time in seconds for sound pressure level to decay by 60 dB after a sound source stops. It is the primary metric used to characterize the acoustic quality of a room. A longer RT60 means more reverb; a shorter one means a drier, more anechoic sound.

What is the difference between the Sabine and Eyring formulas?

The Sabine formula (T = 0.161 V / A) works well for rooms with low absorption (α 0.3), such as recording studios and home theaters. For highly absorptive rooms, Sabine overestimates RT60.

What absorption coefficient should I use?

Absorption coefficients (α) range from 0 (perfectly reflective) to 1 (perfectly absorptive). Concrete or plaster walls are 0.02–0.05. Carpet is 0.30–0.60 depending on thickness. Acoustic foam panels are 0.70–0.95 at mid/high frequencies. Use manufacturer data sheets when available, or standard reference tables for common materials.

What RT60 is ideal for my room?

Recommended RT60 depends on room use: small recording studios and home theaters aim for 0.2–0.4 s; speech-focused spaces (classrooms, conference rooms) target 0.4–0.7 s; small concert halls target 1.4–1.8 s; large symphonic halls often exceed 2.0 s. The ideal also varies by frequency — low frequencies naturally decay more slowly.

Why is RT60 different at each frequency band?

Absorption coefficients for most materials vary significantly with frequency. Thin acoustic foam absorbs high frequencies well but does little at bass frequencies. Bass traps target low frequencies. Running this calculator at 125 Hz, 250 Hz, 500 Hz, 1 kHz, 2 kHz, and 4 kHz separately shows whether your room has a frequency-dependent RT60 problem.

How do I reduce RT60 in a room?

Add absorptive materials — acoustic panels, carpet, heavy curtains, upholstered furniture, or bass traps. Increasing total absorption (sum of area × coefficient) lowers RT60. This calculator shows the current total absorption and target absorption needed to hit a desired RT60, making it easy to plan how much treatment to add.

Reverberation Time RT60 Calculator

Name: Reverberation Time RT60 Calculator
Availability: InStock
Author: Nham Vu

Enter your room dimensions and surface absorption coefficients to calculate RT60 reverberation time using both the Sabine and Eyring formulas.

Room Dimensions

Length (m)

Width (m)

Height (m)

Frequency Band

Room Type (for target reference)

Surface Absorption

List each surface (floor, walls, ceiling, panels). Enter area in m² and absorption coefficient α (0–1).

Enter room dimensions and surfaces, then press Calculate RT60

Summary

Enter your room dimensions and surface absorption coefficients to calculate RT60 reverberation time using both the Sabine and Eyring formulas.

How it works

Enter the room volume (length × width × height in meters).
Add each surface type — floor, walls, ceiling, or custom — with its area and absorption coefficient.
Select the frequency band (125 Hz to 4 kHz) or use the broadband average.
The calculator computes total absorption and applies both Sabine and Eyring formulas.
Results show RT60 in seconds alongside recommended targets for speech, music, or home studio use.
Adjust surface materials or add absorbers and recalculate to reach your acoustic goal.

Use cases

Verify a recording studio or home studio meets acoustic design targets before building.
Estimate how much acoustic treatment is needed to reduce RT60 in a live room.
Compare Sabine vs. Eyring predictions when absorption coefficients are high.
Check whether a conference room or classroom meets speech intelligibility guidelines.
Calculate RT60 at multiple frequency bands to identify boomy bass or harsh highs.
Plan placement and quantity of acoustic panels or bass traps.
Educate audio engineering students on the relationship between room size and decay time.
Validate acoustic treatment changes before and after installation.

Frequently Asked Questions

Last updated: 2026-07-01 · Reviewed by Nham Vu