Rw to transmission coefficient
Type a value in Rw to get it in τ instantly.
1×10⁻⁵τ
That's 3.2× as quiet as a blockwork wall, while a party wall is 2× better. A 75 dB television next door would come through at about 25 dB.
Convert the other way: τ to Rw
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 Rw to τ
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 Rw = 1×10⁻⁵ τ.
Every unit
Your rating in every unit
Tables
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 |
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 |
Quick answers
Quick answers
- How many τ is 1 Rw?
- 1 Rw is 0.794328 τ.
- How many τ is 10 Rw?
- 10 Rw is 0.1 τ.
- How many τ is 50 Rw?
- 50 Rw is 1×10⁻⁵ τ.
The units
About these units
Rw (Rw)
The international weighted sound reduction index, in decibels.
Transmission coefficient (τ)
The fraction of sound energy that gets through.
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