What Cross-Channel Budgeting Does
GA4 is rolling out budget planning tools that bring ad spend forecasting directly into your analytics platform. Until now, comparing performance across Google Ads, Meta, and TikTok meant exporting data into spreadsheets or paying for third-party planning software. That’s changing.
The new cross-channel budgeting feature, currently in beta, includes two tools: projection plans and scenario plans. Projection plans help you track whether your current spending is on pace to hit your targets. Scenario plans let you simulate what would happen if you moved budget from one channel to another.
Both tools use machine learning trained on your historical conversion data to predict outcomes. They work with Google Ads natively, and with non-Google platforms like Meta and TikTok — provided you’ve imported your cost data into GA4.
Why This Matters
Most businesses manage ad budgets in platform-specific dashboards or shared spreadsheets. The numbers from Google Ads live in one place, Meta’s in another, and TikTok’s in yet another. Comparing them means manual exports, formula maintenance, and a lot of context switching.
By building budget planning into GA4, Google is putting forecasting and performance data in the same environment. You can see projected conversions alongside actual analytics data without leaving the platform. It’s a practical step towards making GA4 the single source of truth for paid media performance.
For teams running campaigns across three or more channels, this could save hours of manual reconciliation each month. The predictions aren’t perfect — no forecast is — but having a baseline generated from your own data is more useful than building one from scratch in a spreadsheet.
Projection Plans — Are You on Track?
Projection plans answer a straightforward question: will your current ad spend hit your targets by the end of the period? Think of them as a pacing tool. They show you forecasted spend, conversions, and revenue mapped against the KPIs you’ve defined.
The tool breaks this down by channel, so you can quickly spot which platforms are underspending or overspending relative to their goals. If your Meta campaigns are burning through budget faster than expected while Google Ads is lagging behind, you’ll see that in one view rather than having to check each platform separately.
This is particularly useful mid-campaign. Rather than waiting until the end of the month to review performance, you can make adjustments while there’s still time to course-correct. If projected conversions from one channel are falling short, you can reallocate budget before the shortfall becomes permanent.
How to Set One Up
Setting up a projection plan is fairly straightforward. In GA4, navigate to Advertising > Planning. From there, select the conversion events you want to track — these are the actions that matter most to your business, whether that’s purchases, lead form submissions, or something else.
Next, define your target KPIs and set your total budget along with the time period you’re planning for. GA4 will then generate a projection for each channel based on your historical data. You’ll see a breakdown of expected spend, predicted conversions, and estimated revenue, all compared against your targets.
Review the channel-level projections carefully. The accuracy depends on how much historical data GA4 has to work with, so newer campaigns or recently added channels may produce less reliable forecasts. Google recommends having at least a year of conversion data for the best results, according to their cross-channel budgeting documentation.
Scenario Plans — Where Should the Budget Go?
Where projection plans tell you if you’re on track, scenario plans help you decide where to put your money. They answer the question: what happens if I shift budget from one channel to another?
The tool simulates different budget distributions using machine learning models built from your conversion history. You set a total budget, and GA4 generates recommended allocations across your active channels based on predicted return on investment. It’s not just showing you one option — you can compare multiple scenarios side by side to see how different distributions affect projected outcomes.
This is where the tool gets genuinely useful. Instead of guessing whether an extra £2,000 on TikTok would outperform the same amount on Google Search, you can model both scenarios with data specific to your account. The recommendations account for diminishing returns at higher spend levels, which is something that’s difficult to model accurately in a spreadsheet.
How to Set One Up
Start by choosing your total budget and the time period for your plan. Then select which channels to include in the scenario. You’ll want to include all channels where you have sufficient historical data, as excluding a channel means the model can’t factor it into its recommendations.
GA4 will generate an optimised allocation based on predicted ROI for each channel. You can then adjust the inputs — increase the total budget, remove a channel, change the time period — and compare the resulting scenarios. Each scenario shows projected conversions, revenue, and cost per conversion by channel.
The comparison view is the most valuable part. Being able to see three or four different budget distributions and their predicted outcomes side by side gives you a clearer basis for decision-making. It’s worth running several variations to understand how sensitive your projected results are to budget shifts between channels.
What You Need Before You Start
Cross-channel budgeting won’t work out of the box for every GA4 property. There are a few prerequisites you need to have in place before the tools will generate useful projections.
First, you need at least one year of conversion data in your GA4 property. The machine learning models rely on historical patterns to make predictions, and without enough data, the forecasts will be unreliable or unavailable entirely. If your property is newer than 12 months, you may need to wait before these tools become useful.
Second, you need campaign data from at least two channels, and at least one of those must be a non-Google platform. This means you’ll need to have cost data imports configured for platforms like Meta or TikTok. If you haven’t set this up yet, that’s your first step — the budgeting tools can’t forecast across channels they don’t have data for.
You’ll also need properly configured conversion events and attribution settings. Make sure your key conversions are marked correctly in GA4 and that your Google Ads account is linked to your GA4 property. Without these connections, the data feeding the models will be incomplete.
Finally, check that your attribution model is set appropriately. The budgeting tools use your property’s attribution settings to assign credit across channels, so if your attribution model doesn’t reflect how your customers actually convert, the budget recommendations will be skewed accordingly.
A Note on Data Quality
The accuracy of any forecast depends on the quality of the data going in. If your cost data imports have gaps, or if your conversion tracking has changed significantly in the past year, the projections may not reflect reality. Before relying on these tools for budget decisions, spend some time auditing your data imports and conversion setup.
Google’s GA4 updates page is worth checking periodically as the feature develops, since the requirements and capabilities are likely to evolve while it remains in beta.
Getting Started
Cross-channel budgeting is still in beta, so expect some rough edges and the occasional limitation. The real value here is having forecasting and analytics data in one place, removing the need to juggle multiple exports and spreadsheets to answer basic budget allocation questions.
If you’re already importing cost data from Meta or TikTok into GA4, it’s worth testing. Start with a projection plan for a current campaign — compare the forecast against actual results over a couple of weeks to gauge accuracy. Once you’re confident in the projections, move on to scenario plans to start optimising your budget allocation across channels.
The tools won’t replace strategic thinking about where to invest your ad spend, but they give you a data-driven starting point that’s far more useful than gut instinct or last month’s spreadsheet.
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