Background
Intimate partner violence (IPV) poses a major public health concern. To date there are few rigorous economic evaluations of interventions aimed at preventing IPV in low-income settings. This study provides a cost and cost effectiveness analysis of SASA!, a community mobilisation intervention to change social norms and prevent IPV.

Methods
An economic evaluation alongside a cluster randomised controlled trial. Both financial and economic costs were collected retrospectively from the provider’s perspective to generate total and unit cost estimates over four years of intervention programming. Univariate sensitivity analysis is conducted to estimate the impact of uncertainty in cost and outcome measures on results.

Results
The total cost of developing the SASA! Activist Kit is estimated as US$138,598. Total intervention costs over four years are estimated as US$553,252. The annual cost of supporting 351 activists to conduct SASA! activities was approximately US$389 per activist and the average cost per person reached in intervention communities was US$21 over the full course of the intervention, or US$5 annually. The primary trial outcome was past year experience of physical IPV with an estimated 1201 cases averted (90 % CI: 97–2307 cases averted). The estimated cost per case of past year IPV averted was US$460.

Conclusion
This study provides the first economic evaluation of a community mobilisation intervention aimed at preventing IPV. SASA! unit costs compare favourably with gender transformative interventions and support services for survivors of IPV.