This document specifies methods for calculating an equivalent monopole source level by converting radiated noise level values obtained in deep water according to ISO 17208-1. Procedures are also given for direct calculation from measurements made in deep water with specific hydrophone geometry. The source level calculated by the procedure in this document is that of an equivalent monopole source at a specified nominal source depth, and for broadside aspect only. The nominal source depth is intended to be reported with the equivalent monopole broadside source level value.