Budget is the limiter

Budget and bid strategy do different jobs. The budget limits the amount Google Ads is allowed to spend over time. A target CPA or ROAS changes which auctions the bidder enters and can affect whether the budget is spent.

Using a tight target as a brake can make a campaign ineligible for auctions and cause underspend. It does not follow that the refused clicks were necessarily the best or that cheap clicks necessarily convert worse. The real question is whether efficiency or maximum output is the business constraint.

When the objective is maximum output from fixed spend, a budget with Maximise conversions or Maximise conversion value asks Google to optimise within that spend. It is still a forecast-driven bidder and does not guarantee the business outcome unless the conversion goals and values represent it.

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 began a gradual rollout on 17 August 2026 for affected campaigns that are limited by budget and use target-based bidding. Google says they will deliver more consistently toward the stated target. For a business seeking the highest volume or value from fixed spend, Google documents switching to Maximise conversions or Maximise conversion value without a target as one option. That is the option we normally test; it is a choice of objective, not proof that every target is wrong.

Where the strategy supports a portfolio bid limit, it 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 accounts we manage have a fixed commercial budget. Our operating checklist is: confirm whether that budget actually binds, verify the goals and values, choose the strategy that matches the objective, and check the result weekly. A fixed budget alone does not make a target invalid if efficiency remains the harder business constraint.

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.

Sources checked

• Google Ads: campaign budgets
• Google Ads: August 2026 target rollout
• Google Ads: options for affected campaigns

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