The USAID | DELIVER PROJECT, Task Order 4, developed this guide for quantifying health commodities; it will assist technical advisors, program managers, warehouse managers, procurement officers, and service providers in (1) estimating the total commodity needs and costs for successful implementation of national health program strategies and goals, (2) identifying the funding needs and gaps for procuring the required commodities, and (3) planning procurements and shipment delivery schedules to ensure a sustained and effective supply of health commodities. The step-by-step approach to quantification presented in this guide is complemented by a set of product-specific companion pieces that include detailed instructions for forecasting consumption of antiretroviral drugs, HIV test kits, antimalarial drugs, and laboratory supplies.