Transmission coefficient to Rw
Type a value in τ to get it in Rw instantly.
-16.99Rw
Nothing on our list is smaller: an interior door is 5,000× better. A 75 dB television next door would come through at about 91.99 dB.
Convert the other way: Rw to τ
What it means
How much sound gets through?
STC and Rw use different weighting curves, so the one-decibel offset is a good rule of thumb, not an exact conversion. Both ignore low bass, where walls perform worst.
The math
How to convert τ to Rw
The rating is a logarithm of what gets through: dB = −10 × log₁₀(transmitted fraction). STC runs about one decibel above Rw for ordinary partitions.
Example: 50 τ = -16.9897 Rw.
Every unit
Your rating in every unit
Tables
τ to Rw conversion table
| τ | Rw |
|---|---|
| 20 τ | -13.0103 Rw |
| 25 τ | -13.9794 Rw |
| 30 τ | -14.7712 Rw |
| 35 τ | -15.4407 Rw |
| 40 τ | -16.0206 Rw |
| 45 τ | -16.5321 Rw |
| 50 τ | -16.9897 Rw |
| 55 τ | -17.4036 Rw |
| 60 τ | -17.7815 Rw |
| 65 τ | -18.1291 Rw |
| 70 τ | -18.451 Rw |
Rw to τ conversion table
| Rw | τ |
|---|---|
| 20 Rw | 0.01 τ |
| 25 Rw | 0.00316228 τ |
| 30 Rw | 0.001 τ |
| 35 Rw | 0.000316228 τ |
| 40 Rw | 1×10⁻⁴ τ |
| 45 Rw | 3.162×10⁻⁵ τ |
| 50 Rw | 1×10⁻⁵ τ |
| 55 Rw | 3.162×10⁻⁶ τ |
| 60 Rw | 1×10⁻⁶ τ |
| 65 Rw | 3.162×10⁻⁷ τ |
| 70 Rw | 1×10⁻⁷ τ |
Quick answers
Quick answers
- How many Rw is 1 τ?
- 1 τ is 0 Rw.
- How many Rw is 10 τ?
- 10 τ is -10 Rw.
- How many Rw is 50 τ?
- 50 τ is -16.9897 Rw.
The units
About these units
Transmission coefficient (τ)
The fraction of sound energy that gets through.
Rw (Rw)
The international weighted sound reduction index, in decibels.
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