This calculator allows the internal noise level to be estimated based on the building construction and a specified external noise level. Noise is predicted through the wall facing the road, and optionally through the roof, windows and doors. Both the total noise level and the path contribution is displayed.

Each tab contains different input fields required for the calculation. A PDF of the inputs and result can be generated on the ‘Export’ tab. The PDF file will also contain a link to reopen the calculation at a later date. Help text is available for a number of elements by clicking on the (?) symbols.


This tool provides an estimate of the noise levels inside a building based on the external noise level and the building construction. The tool generally uses the method in EN 12354-3:2000 Building acoustics – Estimation of acoustic performance of buildings from the performance of elements – Part 3: Airborne sound insulation against outdoor sound. The sound reduction indices for the stated elements have been estimated using the Insul software package. In addition to the standard terms and conditions for use of this website, Waka Kotahi NZ Transport Agency does not accept any responsibility or liability whatsoever, whether in contract, tort, equity or otherwise, for any action taken as a result of reliance placed on this tool, or for any error, inadequacy, deficiency, flaw in or omission in the tool.