Inputs
Example data table
| Scenario | Length | Width | Height | Key finishes | Estimated RT60 |
|---|---|---|---|---|---|
| Meeting room | 10 | 8 | 3 | Carpet on pad + acoustic ceiling | ~0.6–0.9 s |
| Hard-surfaced lobby | 18 | 12 | 4 | Tile + concrete + glass | ~1.8–3.0 s |
| Classroom (treated) | 9 | 7 | 3.2 | Ceiling tile + wall panels | ~0.5–0.8 s |
Formula used
- Total absorption (A) = Σ (Areai × αi)
- Average coefficient = A ÷ S, where S is total surface area
- Sabine RT60 = K × V ÷ A
How to use this calculator
- Choose units, then enter room length, width, and height.
- Keep auto areas enabled for standard rectangular rooms.
- Select a finish for each surface, or enter a custom coefficient.
- Add optional surfaces for panels, partitions, or special zones.
- Press Calculate to view absorption, average coefficient, and RT60.
- If you have a target RT60, enter it to estimate extra absorption.
- Use CSV or PDF downloads to share results with your team.
Article
1) What total absorption represents
Total absorption is reported in sabins and equals the sum of each surface area multiplied by its absorption coefficient. Higher sabins mean the room dissipates more sound energy per reflection, reducing echo and improving speech clarity. This calculator lets you compare common finishes and quantify how each one contributes to the overall acoustic balance.
2) Reading the average coefficient
The average coefficient is the ratio of total absorption to total modeled surface area. It helps teams benchmark a design quickly, especially when finishes change late in construction. A higher average value generally indicates a “softer” space that controls reflections better, while low values signal hard, reflective interiors.
3) RT60 and practical targets
RT60 estimates how long sound persists after the source stops. Using the Sabine relationship, RT60 is proportional to room volume and inversely proportional to total absorption. Many meeting rooms and classrooms aim for shorter reverberation times than lobbies or atriums because intelligibility matters more than “liveness.” Use the target RT60 feature to see the additional absorption required for your chosen criterion.
4) Treatment sizing with real constraints
When a target RT60 is entered, the calculator determines the absorption required and the shortfall versus the current design. If you provide a treatment coefficient, it converts that shortfall into an estimated treatment area. Comparing this area to available wall or ceiling space highlights whether panels, baffles, or upgraded ceilings are feasible within the geometry.
5) Construction decisions and documentation
Acoustic performance is often influenced by finish substitutions, ceiling layout, and added partitions. This tool supports scenario planning by letting you add extra surfaces for specialty products and then export results for coordination. Always confirm final coefficients using manufacturer data and consider noise sources, occupancy, and HVAC design when setting project targets. Document assumptions for traceability.
FAQs
1) What is a sabin?
A sabin is one unit of sound absorption, equal to one unit of area with an absorption coefficient of 1.0 at a given frequency band. It’s used to sum absorption contributions across surfaces.
2) Why does RT60 change when room size changes?
RT60 scales with volume. Larger rooms store more sound energy and need more absorption to achieve the same decay time. Increasing absorption without increasing volume typically reduces RT60.
3) Which coefficients should I use for design?
Use verified product data whenever possible. Default coefficients are typical mid-frequency references for early planning. For procurement and compliance, use laboratory-tested values for the exact product, thickness, and mounting.
4) Does this account for people and furniture?
No. Occupants, seating, and furnishings add absorption, especially at mid and high frequencies. For occupied conditions, add extra surfaces or adjust coefficients to reflect expected furnishings and seating density.
5) When should I use the target RT60 option?
Use it when you have an acoustic requirement or a performance goal. It estimates how much additional absorption is needed and helps convert that need into treatment area when a treatment coefficient is provided.
6) Why might measured results differ from the estimate?
Sabine estimates assume diffuse sound fields and typical behavior. Real spaces have geometry effects, frequency dependence, openings, and leakage. Field measurements also vary with equipment, placement, and background noise.
7) Can I model partial coverage or mixed finishes?
Yes. Enter additional surfaces for panels or zones, or disable auto areas and input your own surface areas. Mixed finishes can be represented by splitting a surface into multiple entries with different coefficients.