Leak Sizer is an advanced instrument for leak location and for the determination of leak size probability. The algorithms within the Leak Sizer software analyse the recorded leak sound to extract a range of key features. These can be correlated using probability against leak size. The sizing process is divided into two categories; communication/services pipes (less than 50mm) and mains pipes (greater than 50mm). The leak size estimate probability is displayed in three categories for the smaller pipes and into two categories for the larger pipes.