Google Ads budget forecasts for 2027 should not be built by adjusting historic CPC and adding a percentage growth target. A more defensible model links spend to market capacity, attainable acquisition costs and supply constraints.
Five inputs for the forecast
Start with market capacity: assess how many searches in the target geography are likely to convert and how many are available under the account's bidding model. Keyword Planner and reach data can help set the upper limit for forecast conversions.
The demand curve by bid is equally important. Collect data on how CPC and impression share change as bids rise across account segments. Higher spend does not bring conversions at the same price, so a linear extrapolation can misstate both volume and cost.
Compare acquisition costs across search, display networks and other channels available to the vertical. Budget can then shift toward the channels with a lower marginal conversion cost. Monthly demand patterns should also replace annual CPC averages, with changes in impression share showing where bidding limits are reached.
Supply constraints must be included before allocating funds. Inventory, moderation and the availability of audience segments can limit conversions even when demand exists.
Building the budget
Set market capacity first, then estimate conversion costs at different bid levels and map the seasonal demand profile. The resulting budget combines available volume with the marginal price, subject to supply constraints. A growth target then becomes the outcome of the calculation rather than its starting point. For verticals with expensive clicks, this monthly view gives a clearer picture of what the account is paying for.
