Voluntary Medical Male circumcision (VMMC) has been part of prevention in Namibia since 2009. Yet, as of 2013, VMMC coverage among 15- to 24-year-olds was estimated at less than 22%. Program data suggests uptake of VMMC below age 15 is lower than expected, given the age distribution of the eligible population. Nearly 85% of VMMCs were for males between ages 15 and 29, while boys 10–14 years were referred outside the program. This analysis uses the Decision Makers Program Planning Tool to understand the impact of age prioritization on circumcision in Namibia. Results indicate that circumcising males aged 20–29 reduced HIV incidence most rapidly, while focusing on ages 15–24 was more cost effective and produced greater magnitude of impact. Providing services to those under 15 could increase VMMC volume 67% while introducing Early Infant Medical Circumcision could expand coverage. This exercise supported a review of VMMC strategies and implementation, with Namibia increasing coverage among 10- to 14-year-olds nearly 20 times from 2016 to 2017.