There is no universal ‘good ACoS’. Your break-even is your contribution margin percentage — category-specific, often SKU-specific, and the only honest bid ceiling.

A 6x ROAS on branded keywords usually means you paid for sales you would have made anyway. The buyer typed your brand name; they were already coming. Attribution credits the ad, the dashboard looks great, and actual profit went down by the cost of the click.

Separate branded from non-branded, defensive from acquisition, and measure incrementality — the sales that would not have happened without the spend. Then optimise against contribution margin after commission, fulfilment, returns and GST.

Your break-even ACoS is that contribution margin percentage. A 40% ACoS can be excellent on a high-margin beauty SKU and catastrophic in low-margin electronics — calculate it per SKU before setting any bid.

For launches, budget the full window upfront: new listings typically need six to ten weeks of deliberately unprofitable spend to build ranking and review velocity. Stopping halfway wastes the entire spend — anyone promising faster is selling you ad spend, not growth.