Method and definitions
CPC = historical spend ÷ historical clicks. Planned clicks = budget ÷ CPC. Estimated leads = planned clicks × click-to-lead rate. CPL = CPC ÷ conversion rate.
Historical clicks must be positive. Zero historical media spend gives zero CPC, but cannot support a paid-click forecast. Zero conversion rate yields zero estimated leads and undefined CPL. Forecasts assume stable CPC and conversion; actual auction costs and delivery vary.