RT60 Reverberation Time Calculator
Calculate estimated room reverberation time (RT60) using room dimensions and surface absorption coefficients via Sabine and Eyring formulas.
Surface Materials & Areas
| Surface / Material Description | Area (m²) | Absorption (α) | Subtotal (Sabins) | Action |
|---|
Calculate RT60 and Plan Better Room Acoustics
An RT60 calculator estimates how long sound remains audible inside a room after the sound source stops. Specifically, RT60 measures the time required for sound energy to decay by 60 decibels (dB). This value is widely used when designing recording studios, home theaters, listening rooms, classrooms, auditoriums, and other acoustic spaces.
Instead of performing multiple calculations by hand, this calculator estimates room reverberation time using your room dimensions and the absorption properties of individual surfaces. It calculates Sabine RT60, Eyring RT60, total sound absorption, and the average absorption coefficient, helping you evaluate how changes in room materials may affect acoustic performance before purchasing treatment.
Because every calculation updates instantly as dimensions or materials change, you can quickly compare different room designs and treatment options.
How the RT60 Calculator Works
The calculator first determines the room’s geometry.
Room Volume (V) = Length × Width × Height
Total Surface Area (S) = 2 × ((Length × Width) + (Length × Height) + (Width × Height))
Each room surface contributes sound absorption according to its area and absorption coefficient.
Total Absorption (A) = Σ (Surface Area × Absorption Coefficient)
The calculator then determines the room’s average absorption coefficient:
Average Absorption (ᾱ) = Total Absorption ÷ Total Surface Area
Finally, it calculates reverberation time using both of the industry’s most common acoustic equations:
- Sabine RT60 = (Constant × Room Volume) ÷ Total Absorption
- Eyring RT60 = (Constant × Room Volume) ÷ (−Total Surface Area × ln(1 − ᾱ))
The correct constant is automatically selected for either metric or imperial units.
If you already know the total absorption of your room, the dedicated Absorption Coefficient Calculator can calculate these values directly.
Understanding the Results
The calculator displays several values that describe the acoustic behavior of your room.
| Output | Meaning |
|---|---|
| Sabine RT60 | Reverberation estimate using the Sabine equation |
| Eyring RT60 | Reverberation estimate using the Eyring equation |
| Total Absorption | Combined sound absorption of all room surfaces |
| Average Absorption Coefficient | Overall absorption efficiency of the room |
Because the calculator updates every value in real time, you can immediately see how changing materials or room dimensions affects reverberation.
Sabine vs. Eyring RT60
Both formulas estimate reverberation time, but they perform best under different acoustic conditions.
Sabine Formula
The Sabine equation is the traditional RT60 model and generally works well for rooms with relatively low average absorption. It is commonly used when the average absorption coefficient remains below approximately 0.3, such as untreated or lightly treated rooms.
Eyring Formula
The Eyring equation accounts for higher overall absorption and usually predicts shorter reverberation times in heavily treated spaces. As more acoustic panels, bass traps, carpets, and absorptive finishes are added, the Eyring estimate often becomes more representative of real-world performance.
For additional guidance on suitable reverberation targets, the Ideal RT60 article explains recommended decay times for different room types.
How to Use the RT60 Calculator
Using the calculator only takes a few steps.
- Select Metric or Imperial units.
- Enter your room’s length, width, and height.
- Review or edit the listed room surfaces.
- Select the appropriate material or enter a custom absorption coefficient for each surface.
- Add or remove surfaces as needed.
- Review the calculated RT60 values, total absorption, and average absorption coefficient.
The calculator automatically recalculates every result whenever you modify the room dimensions or surface properties.
If you need help choosing absorption values, the Absorption Coefficients Guide explains how different materials influence sound absorption.
Practical Applications
RT60 calculations are useful for many acoustic projects, including:
- Recording studios.
- Home theaters.
- Podcast rooms.
- Listening rooms.
- Classrooms.
- Offices.
- Conference spaces.
Estimating reverberation before purchasing treatment helps you make more informed decisions about acoustic panels, bass traps, carpets, ceiling treatments, and other sound-absorbing materials.
For complete room planning, the Room Acoustics Calculator estimates room modes and surface area, while the Room Acoustics Guide explains how room dimensions influence acoustic performance.
Tool Limitations
This calculator provides mathematical estimates based on the room dimensions and material properties you enter.
It does not:
- Measure RT60 using a microphone.
- Analyze recorded audio.
- Replace professional acoustic testing.
- Simulate speaker placement or furniture.
- Predict every reflection inside a real room.
Actual reverberation time may vary because furniture, occupancy, irregular geometry, and treatment placement all influence acoustic behavior.
For additional treatment advice, the Acoustic Treatment Guide, Bass Traps Guide, and Home Studio Acoustics provide practical recommendations for improving room acoustics.
Frequently Asked Questions
What is RT60?
RT60 is the time required for sound energy to decay by 60 dB after the sound source stops. It is one of the most widely used measurements of room reverberation.
Why does the calculator show both Sabine and Eyring RT60?
The Sabine formula is generally suitable for rooms with relatively low average absorption, while the Eyring formula typically provides more realistic estimates for heavily treated rooms with higher absorption.
Does this calculator measure my room?
No. It performs mathematical calculations using the room dimensions, surface areas, and absorption coefficients that you enter.
Can I add my own room materials?
Yes. You can add, edit, or remove room surfaces and specify custom absorption coefficients for each one.
Why do RT60 values change when I change the materials?
Different materials absorb different amounts of sound energy. Increasing total absorption usually reduces the calculated reverberation time.