Physics

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Physics

Acoustic Room Reverb Time Calculator.

Estimates the reverberation time (RT60) of a room based on its volume, total surface area, and average absorption coefficient, using the Sabine formula.

Results update live as you type.
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Your inputs

How it works

  1. 1

    Enter the room volume in cubic meters.

  2. 2

    Enter the total surface area of all room boundaries in square meters.

  3. 3

    Enter the average absorption coefficient (between 0 and 1).

  4. 4

    The calculator applies the Sabine formula to estimate RT60.

0.161 * volume / (surface_area * absorption_coefficient)

Frequently asked questions

What is RT60?

RT60 is the time it takes for a sound to decay by 60 decibels after the source stops. It indicates how reverberant a room is.

What is a good RT60 for a room?

It depends on the use: about 0.4–0.6 s for speech, 1.5–2.0 s for concert halls, and 0.2–0.4 s for recording studios.

How accurate is the Sabine formula?

It works well for rooms with average absorption below 0.3 and fairly diffuse sound fields. For highly absorptive rooms, the Eyring formula is more accurate.

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Reverberation Time (RT60)

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Estimate for general guidance only — verify important decisions with an appropriate professional.

How it works

Estimates the reverberation time (RT60) of a room based on its volume, total surface area, and average absorption coefficient, using the Sabine formula.

  1. Enter the room volume in cubic meters.
  2. Enter the total surface area of all room boundaries in square meters.
  3. Enter the average absorption coefficient (between 0 and 1).
  4. The calculator applies the Sabine formula to estimate RT60.

Formulas

The math behind this calculator, written out so you can verify the result.

Sabine Formula

RT60 = 0.161 × V / (A × α)

V is room volume in m³, A is total surface area in m², α is average absorption coefficient.

Example:

Input: V = 100 m³, A = 150 m², α = 0.2

Calculation: 0.161 × 100 / (150 × 0.2)

Result: ≈ 0.54 s

Real-world use cases

Where this calculation shows up in everyday life.

Home Theater Setup

Estimate reverb time to decide on acoustic panels for clearer dialogue.

Example: A 50 m³ room with α=0.15 gives RT60 ≈ 1.07 s, which may be too echoey.

Recording Studio Design

Check if a room meets the low RT60 needed for clean recordings.

Example: A 80 m³ studio with α=0.4 gives RT60 ≈ 0.32 s, suitable for tracking.

Classroom Acoustics

Ensure speech intelligibility by keeping RT60 below 0.6 s.

Example: A 200 m³ classroom with α=0.25 gives RT60 ≈ 0.64 s, borderline.

Tips and common mistakes

Tips

  • Measure volume and surface area accurately for better estimates.
  • Use average absorption coefficients from material tables.
  • For rooms with high absorption (α > 0.3), consider the Eyring formula.
  • RT60 varies with frequency; this calculator gives a broadband estimate.

Common Mistakes to Avoid

  • Using the floor area instead of total surface area.
  • Entering absorption as a percentage (e.g., 20 instead of 0.2).
  • Ignoring that the formula assumes a diffuse sound field.

Assumptions and limitations

  • Use the stated inputs and units.
  • Results are estimates for planning and education.
  • Check measurements and source data before making an important decision.