Full Answer

The feature sits inside GA4's Advertising section and introduces two planning tools. Projection plans take your historical spend and conversion data for each channel — Google Ads, Meta, TikTok, email — and forecast future performance at a given budget level. Scenario plans go a step further: you drag budget between channels and GA4 models the projected outcome of each reallocation before you commit a dollar. Together they turn GA4 from a reporting tool into a planning surface.

The catch is data completeness. Google Ads cost data flows in natively, but every other channel — Meta, TikTok, LinkedIn, programmatic — requires a manual or connector-based cost import. Without those imports, GA4 can only project on the channels it can see, and the cross-channel model runs on a partial picture. For most WooCommerce stores, this means the forecasts lean heavily on Google's own channels while underweighting the rest of the media mix.

The 42% ROI improvement from cross-channel planning only materialises when the planner has full visibility. If your GA4 instance is forecasting with incomplete cost data, the projections can steer budget toward channels that simply report more, not channels that perform better. For a deeper look at what GA4's forecasting actually sees, read [GA4 Now Forecasts Your Budget — But It's Forecasting With 9-Carat Data](https://seresa.io/blog/ga4-reporting-accuracy/ga4-now-forecasts-your-budget-but-its-forecasting-with-9-carat-data).