Google Performance Planner is a forecasting tool inside Google Ads that models how different budget and bid scenarios will affect your campaign metrics like clicks, conversions, and conversion value. You input potential budgets, and it shows projected outcomes based on historical auction data, seasonality, and landing page performance. The core benefit is budget optimization across campaigns. If you're running five campaigns with $20,000 total monthly spend, Performance Planner tells you whether shifting $3,000 from Brand to Shopping will yield more conversions. It accounts for diminishing returns, so you see when adding another $1,000 to a maxed-out campaign produces minimal lift versus reallocating that money elsewhere. It's particularly valuable for quarterly planning. Most Canadian businesses see seasonal swings (Q4 retail spikes, summer slowdowns for B2B), and Performance Planner incorporates these patterns. You can model Black Friday budgets in September or plan RRSP season campaigns for financial services in January and February. Limitations matter. The tool works best with campaigns that have conversion tracking installed and at least 3–4 months of stable data. If you're spending under $3,000 monthly or running brand-new campaigns, the forecasts are too broad to be actionable. It also assumes your landing pages and ad copy stay constant, so if you're planning a site redesign, the projections won't account for potential conversion rate changes. At Ottawa SEO, we use Performance Planner for clients spending $8,000+ monthly to set quarterly budgets, then validate its recommendations against actual performance in the first two weeks. We've found its conversion forecasts are typically within 15–20% of reality for established campaigns, but cost-per-conversion estimates can swing 25–30% depending on competitor activity it can't predict. Treat it as directional guidance for allocation decisions, not a guarantee, and always reserve 10–15% of budget for testing new campaign structures the planner can't model.