Reverberation Time Calculator
Calculate the reverberation time (RT60) of a room using the Sabine equation T = 0.161V/A, where V is room volume and A is total absorption. Essential for architectural acoustics and audio design.
This free online reverberation time calculator provides instant results with no signup required. All calculations run directly in your browser — your data is never sent to a server. Enter your values below and see results update in real time as you type. Perfect for everyday calculations, homework, or professional use.
Minimum: 0
Results
Reverberation Time (RT60)
1.61 s
How to Use This Calculator
Enter your input values
Fill in all required input fields for the Reverberation Time Calculator. Most fields include unit selectors so you can work in your preferred unit system — metric or imperial, whichever matches your problem.
Review your inputs
Double-check that all values are correct and that you have selected the right units for each field. Incorrect units are the most common source of calculation errors and can produce results that are off by factors of 2, 10, or more.
Read the results
The Reverberation Time Calculator instantly computes the output and displays results with units clearly labeled. All calculations happen in your browser — no loading time and no data sent to a server.
Explore parameter sensitivity
Try adjusting individual input values to see how the output changes. This is a quick and effective way to develop intuition about how different parameters influence the result and to identify which inputs have the largest effect.
When to Use This Calculator
- •Use the Reverberation Time Calculator when you need accurate results quickly without the risk of manual computation errors or unit conversion mistakes.
- •Use it to verify calculations made by hand or in spreadsheets — an independent check can catch errors before they lead to costly decisions.
- •Use it to explore how changing input parameters affects the output — a quick way to develop intuition and identify the most influential variables.
- •Use it when collaborating with others to ensure everyone is working from the same numbers and applying the same assumptions.
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About Reverberation Time Calculator
The Reverberation Time Calculator uses the Sabine equation to determine how long sound persists in a room after the source stops. RT60, the time for sound to decay by 60 dB, is the primary metric in architectural acoustics. Developed by Wallace Clement Sabine at Harvard in 1898, this equation launched the science of room acoustics. Ideal RT60 varies by purpose: concert halls need 1.5-2.5 seconds for music to blend beautifully, while speech requires 0.4-0.8 seconds for clarity. Recording studios, classrooms, and theaters each demand carefully engineered reverberation.
The Math Behind It
Formula Reference
Sabine Equation
T₆₀ = 0.161V/A
Variables: V = room volume (m³), A = total absorption (Σαᵢ × Sᵢ) in m² sabins
Worked Examples
Example 1: Lecture Hall
V = 500 m³, A = 80 m² sabins (moderate absorption)
RT60 of 1.01 s — suitable for lectures with some treatment.
Example 2: Concert Hall
V = 15,000 m³, A = 3,500 m² sabins
RT60 of 0.69 s — too dry for orchestral music; needs less absorption.
Common Mistakes & Tips
- !Using room surface area instead of room volume — the Sabine equation uses volume (m³).
- !Confusing absorption area (sabins) with physical surface area — A = α × S, not just S.
- !Applying Sabine's equation to very dead rooms (high absorption) where the Eyring equation is more appropriate.
- !Ignoring frequency-dependent absorption — RT60 often varies significantly across the frequency spectrum.
Related Concepts
Frequently Asked Questions
What makes a concert hall sound good?
Optimal RT60 (1.8-2.2 s for orchestral music), uniform diffusion (no echoes or dead spots), strong early reflections for clarity, and adequate loudness. Famous halls like Vienna's Musikverein and Boston Symphony Hall have RT60 around 2 seconds.
How do I reduce room echo?
Add absorptive materials: carpets, heavy curtains, upholstered furniture, acoustic panels, and bookshelves. Focus on hard, parallel surfaces that create flutter echoes. Professional treatment uses broadband absorbers and diffusers strategically placed.
Why do empty rooms sound echoey?
Furnishings, carpets, and people add significant absorption. An empty room has mostly hard, reflective surfaces (walls, floor, ceiling) with low absorption coefficients, resulting in long reverberation times.
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