Enter dimensions, choose units, and pick surface materials. Get volume, absorption, and RT60 instantly below. Download CSV and PDF to share acoustic plans fast.
| Room (L×W×H) | Floor (α) | Ceiling (α) | Walls (α) | Extra (sabins) | Method | RT60 (s) |
|---|---|---|---|---|---|---|
| 6×4×3 m | Carpet on pad (0.40) | Acoustic ceiling tile (0.60) | Plaster on brick (0.03) | 4.00 | Sabine | ~0.39 |
| 20×15×8 m | Wood floor (0.10) | Gypsum board (0.05) | Painted concrete (0.02) | 100.00 | Eyring | ~2.30 |
Reverberation time (RT60) estimates how long it takes sound to decay by 60 dB after the source stops. The calculator uses your room volume (V), total surface area (S), and total absorption (A).
RT60 is the time your room needs to drop by 60 dB after a sound stops. It captures how “live” or “dead” a space feels. Long RT60 improves music blend but reduces speech clarity. Short RT60 improves intelligibility but can sound dry for music, cinema, and podcast recording.
Sabine works best when average absorption is low to moderate and the sound field is fairly diffuse, common in untreated rooms. Eyring is more accurate when absorption is higher, because it uses a logarithmic term that accounts for diminishing returns as ᾱ approaches 1. Many treated studios prefer Eyring.
Small offices and classrooms often aim near 0.4–0.8 s for clear speech. Conference rooms commonly target 0.3–0.6 s. Living rooms may feel comfortable around 0.4–0.7 s. Small music practice rooms can sit around 0.6–1.0 s, depending on style and loudness.
Volume drives reverberation: doubling volume roughly doubles RT60 when absorption stays constant. Surface area also matters because it multiplies each material’s absorption. Enter accurate length, width, and height, and use the unit switch if you measure in feet instead of meters. Even a 10% dimension error can shift RT60.
Each surface has an absorption coefficient α between 0 and 1. Hard plaster and glass are typically low, while heavy curtains, carpet, and acoustic tiles are higher. Coefficients vary by frequency, so your input is a broadband approximation useful for planning and comparisons. If you have datasheets, choose values near 500–1000 Hz.
Occupants and furniture add absorption beyond walls and ceilings. This calculator lets you include a number of seated people plus optional added panels. For a quick estimate, each person contributes a small equivalent absorption area, which can noticeably reduce RT60 in small rooms. Seating, bookcases, and thick sofas behave similarly.
Along with RT60, the results block shows volume, total surface area, total absorption area, and the average absorption ᾱ. If ᾱ is very small, the room will ring and echoes become obvious. If ᾱ is high, further treatment yields smaller improvements and Eyring is usually preferred. Use the CSV to compare design iterations.
To reduce RT60, increase absorption with carpet, curtains, acoustic ceiling tiles, or broadband panels on reflective walls. To preserve brightness while controlling echoes, treat first-reflection points and add diffusion. To lengthen RT60, remove soft materials and add reflective finishes. A balanced approach keeps clarity without making the room feel “dead”.
Q: What is the difference between RT60 and echo?
RT60 is a global decay time for the whole room. Echo is a distinct repeat caused by strong reflections, often between parallel surfaces. A room can have a short RT60 yet still produce flutter echo.
Q: Why does the calculator ask for surface materials?
Reverberation depends on how much sound each surface absorbs. Materials supply absorption coefficients that convert surface area into absorption area. More absorption area generally means a shorter RT60.
Q: Should I use metric or imperial units?
Use whatever you measured. The calculator converts the constant automatically: 0.161 for meters and 0.049 for feet. Keep dimensions consistent within the chosen unit system.
Q: When should I choose Eyring over Sabine?
Choose Eyring when the room is heavily treated or has high average absorption. Sabine can overestimate RT60 in that case. If ᾱ looks relatively high, Eyring is usually safer.
Q: How accurate are the absorption coefficients?
They are typical broadband estimates. Real coefficients depend on frequency, mounting, thickness, and manufacturer data. For better accuracy, replace presets with measured or published coefficients for your exact products.
Q: How do people change reverberation time?
People absorb mid and high frequencies, adding effective absorption area. In small rooms, a few occupants can noticeably reduce RT60. The effect is smaller in large halls because volume dominates.
Q: What RT60 is best for speech rooms?
Many speech-focused rooms target roughly 0.3–0.8 seconds depending on size and background noise. Smaller, quieter rooms generally work better with shorter RT60 for higher clarity.
Tip: If you are comparing multiple designs, export CSV after each run and keep notes about material changes and placement.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.