There is no universal good ACOS — the only figure that matters is your break-even ACOS, which equals your profit margin before ad spend. If your product carries a 35% margin after all Amazon fees and COGS, then a 35% ACOS is break-even, anything below is profit, and anything above is bought at a loss. Most established sellers target 15–25%, but a launch may run 60% deliberately.
Why the 'industry average' is a trap
Averages circulate in the 20–30% range, but they mix a supplement seller with a 60% margin and an electronics reseller with a 12% margin. Copying someone else's target ACOS means copying their cost structure, which you do not share.
A 40% ACOS is excellent if your margin is 55%. The same 40% is destroying money if your margin is 30%. The number alone is meaningless without the margin behind it.
Calculate yours instead
Take your selling price and subtract COGS, the Amazon referral fee (usually 15%), FBA fulfilment, storage, returns allowance and any shipping to Amazon. Divide what remains by the selling price. That percentage is your break-even ACOS.
Then set a target below it. The gap between your target and break-even is your profit per advertised sale.
When a high ACOS is the right decision
During a launch, you are buying rank and review velocity, not immediate profit. Running above break-even for a defined window is a legitimate investment provided you have decided the window in advance and are tracking organic rank as the return.
Defending a hero keyword against a competitor can also justify an elevated ACOS on that specific term, because losing the position costs more than the overspend.
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