ACOS vs ROAS: same number, inverted

Direct answer: ROAS is 100 ÷ ACOS (when ACOS is a percent). A 25% ACOS is a 4x ROAS. They are the same campaign fact, inverted. Neither one is profit. Break-even ACOS is the ceiling; TACOS tells you if ads are replacing organic. Use the ROAS calculator if you think in multiples instead of percents.

Stop mixing the three

You hear	It actually is	Use it to
“We need 4x ROAS”	25% ACOS	Set a campaign target — only after you know break-even.
“ACOS is fine”	Maybe. TACOS might be climbing.	Check organic share the same week.
“ROAS dropped in Q4”	Fees and CPCs moved the ceiling	Recalculate break-even, then the ROAS target.