Budget is the limiter

Two controls limit spend in a Google Ads campaign: the budget and the target. Most accounts use both, and use the wrong one.

Using the target as a brake means setting it tight enough that Google refuses auctions and the campaign underspends. It works, in the sense that spend stays down. It also means the campaign is passing on the clicks that would have been the best ones, because a tight average target can only be held by buying cheap.

Using the budget as the limiter means setting the daily budget from what you can spend and letting the values steer the bidding. The machine spends the budget on the best available outcomes and the budget stops it there.

How this used to work, and what changed

Before 17 August 2026 there was a comfortable halfway house: a target set with enormous headroom. An account we ran had a target CPA of £1,000 on a portfolio strategy with an actual CPA around £300. The target never bound, the budget controlled spend, and one number changed when the client changed what they could afford.

Google's 17 August change ended that arrangement. On a budget-limited campaign the target is now a setpoint, not a ceiling: a campaign delivering well under its target can be walked up toward it. Headroom stopped being free. The honest version of this page's advice is now simpler than it used to be: on a fixed budget, the target box should be empty. Maximise conversions, or maximise conversion value where the values are real, and let the budget do the constraining. The full argument, including why there is no safe number to type instead, is in There is no right number for the target box.

A maximum CPC cap on the portfolio can stay as the backstop against a runaway auction, checked weekly, because a backstop that starts binding has become a second constraint.

What "everything else is noise" means

Most of the industry debate around 17 August was about advertisers with unconstrained budgets and how their targets would behave. Almost nobody is that advertiser. If you have a fixed budget the setup is: budget limits spend, no target, values are real, check it weekly.

Where a target does still matter

If the budget genuinely does not bind, a target ROAS derived from your margin is the instruction that connects the account to the economics: you are telling the machine to buy all the value available at that return. And if a contract or cashflow makes efficiency a hard limit, a target is a deliberate stop loss, kept in the full knowledge that it now binds. Both are choices about your objective, not default settings.

Targets from unit economics · There is no right number for the target box