Reverb Calculator

By CalculatorBolt Team | Published: | Updated: | Reviewed by: Music & Audio Editor

Calculate the reverb time (RT60) of any room based on its dimensions and surface materials. Enter your room's length, width, height, and the absorption coefficients of its surfaces to get an accurate RT60 measurement, acoustic classification, and visual decay graph. Based on the Sabine formula, this tool is informational only—consult an acoustics professional for detailed analysis.

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Calculate RT60

Room Dimensions (meters)

Room length in meters
Room width in meters
Room height in meters

Surface Materials

Surface Area (m²) Absorption Coefficient (α) Actions

Common Material Absorption Coefficients

Material Absorption Coefficient (α)
Concrete/Brick Wall0.01 - 0.02
Painted Plaster0.02 - 0.03
Glass Window0.18 - 0.25
Wooden Floor0.10 - 0.15
Carpet (thin)0.20 - 0.30
Carpet (thick)0.40 - 0.50
Heavy Curtains0.50 - 0.70
Acoustic Panels0.60 - 0.90
Upholstered Furniture0.25 - 0.40
People (per person)0.40 - 0.50

Import/Export Configuration

How It Works

The reverb time (RT60) is calculated using the Sabine formula:

RT60 = 0.161 × (Volume / Total Absorption)

We calculate the room's volume from its dimensions (length × width × height) and determine the total absorption by summing the product of each surface area and its absorption coefficient. The Sabine constant (0.161) is derived from the speed of sound and logarithmic decay principles.

Inputs Explained

Room Dimensions
The length, width, and height of your room in meters. These determine the room's volume, which is a key factor in reverberation time.
Surface Materials
Each surface in your room (floors, walls, ceiling, windows, etc.) with its corresponding area and absorption coefficient.
Absorption Coefficient (α)
A value between 0 and 1 representing how much sound a material absorbs. 0 means perfect reflection (no absorption), 1 means perfect absorption (no reflection). Hard surfaces like concrete have low coefficients (~0.01), while soft materials like acoustic panels have high coefficients (~0.80).

Example

Scenario: A living room with dimensions 5m × 4m × 2.5m.

  • Floor (carpet): 20 m² × 0.30 = 6.0 m² Sabines
  • Ceiling (plaster): 20 m² × 0.02 = 0.4 m² Sabines
  • Walls (painted): 70 m² × 0.03 = 2.1 m² Sabines
  • Windows: 4 m² × 0.18 = 0.72 m² Sabines
  • Furniture: ~5 m² × 0.30 = 1.5 m² Sabines

Volume: 5 × 4 × 2.5 = 50 m³

Total Absorption: 6.0 + 0.4 + 2.1 + 0.72 + 1.5 = 10.72 m² Sabines

RT60: 0.161 × (50 / 10.72) ≈ 0.75 seconds

Classification: Average (suitable for a living room)

Tips & Notes

  • Hard surfaces (concrete, glass, tile) have low absorption coefficients and increase reverb time, creating a more "live" sound.
  • Soft surfaces (carpets, curtains, acoustic panels) have high absorption coefficients and decrease reverb time, creating a more "dead" or controlled sound.
  • RT60 is the time it takes for sound to decay by 60 decibels from its initial level—the standard measurement for room acoustics.
  • Larger rooms naturally have longer reverb times due to increased volume.
  • For critical listening environments (recording studios, home theaters), aim for RT60 values between 0.2 and 0.4 seconds.
  • The Sabine formula works best for rooms with evenly distributed absorption; complex room shapes may require more advanced modeling.
  • Frequency matters: absorption coefficients vary by frequency. This calculator uses broadband averages.

Frequently Asked Questions

It depends on the room's use. Recording studios aim for less than 0.3 seconds to ensure clarity and control. Living rooms typically target 0.4-0.6 seconds for comfort. Classrooms and meeting rooms work well at 0.6-1.0 seconds. Concert halls and auditoriums usually have 1.0-2.0 seconds for rich, immersive sound.

RT60 is calculated using the Sabine formula: RT60 = 0.161 × (Volume / Total Absorption). Volume is measured in cubic meters, and total absorption is the sum of each surface area multiplied by its absorption coefficient, measured in square meters Sabine.

The Sabine formula is an equation developed by Wallace Clement Sabine in the early 1900s to relate room volume, surface absorption, and reverberation time. It states that RT60 = 0.161 × (V / A), where V is volume in cubic meters and A is total absorption in square meters Sabine. It's the foundation of modern architectural acoustics.

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RT60 is the time it takes for sound to decay by 60 decibels (dB) from its initial level. It's the standard measurement for reverberation time in a room and a key metric in architectural acoustics.

Room reverberation is affected by three main factors: room volume (larger rooms have longer reverb), surface materials (hard surfaces reflect sound, soft surfaces absorb it), and the total surface area available for absorption. Room shape and geometry also play a role in more complex scenarios.

Typical absorption coefficients range from 0 (perfect reflection) to 1 (perfect absorption). Examples: concrete walls (0.01-0.02), painted plaster (0.02-0.03), glass windows (0.18), wooden floors (0.10-0.15), thin carpets (0.20-0.30), thick carpets (0.40-0.50), heavy curtains (0.50-0.70), and acoustic panels (0.60-0.90).

This calculator uses the Sabine formula, which provides good estimates for most rectangular rooms with evenly distributed absorption. However, real-world acoustics can be more complex due to room shape, non-uniform surfaces, frequency-dependent absorption, and diffusion effects. For critical applications or complex spaces, consult an acoustics professional.

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