Break-even ACoS Calculator
Price, COGS, Amazon fees — out comes the ACoS where your ads stop making money, and the target I'd actually run. This is the number most sellers skip, then wonder why 'good' campaigns lose money.
Why break-even ACoS is the number that matters
Your break-even ACoS is just your pre-ad profit margin expressed as a percentage of price. Sell at $29.99 with $7.50 COGS and $10.00 in Amazon fees, and you keep $12.49 — a 41.6% margin. Run ads at 41.6% ACoS and every ad-attributed sale nets exactly zero.
Every bid decision flows from this number. It tells you which keywords you can afford, when to cut a bleeding search term, and whether a "great" 30% ACoS campaign is actually printing money or quietly draining it.
What is break-even ACoS?
Break-even ACoS is your profit margin before ad spend: (price − COGS − Amazon fees) ÷ price × 100. At that ACoS, an ad-attributed sale makes exactly $0. Below it, ads are profitable; above it, every click loses money.
How do I set a target ACoS from break-even?
A common practice is targeting around 70% of break-even so each sale keeps real margin after ads. If break-even is 40%, a ~28% target protects profit while leaving room to compete.
When is running above break-even ACoS okay?
During launch or ranking pushes. Ad sales drive organic rank, so briefly buying velocity at or above break-even can pay back in organic sales — as long as it's a deliberate phase with an exit, not a leak.
What counts as Amazon fees here?
Referral fee (typically 15%) plus FBA fulfillment fee per unit, and storage if material. Use your per-unit numbers from Seller Central's revenue calculator for accuracy.
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