Break-even ACOS calculator.
Find the exact ad spend your margin can support before you lose money, then check any campaign against it.
Get a free audit ↗Break-even ACOS equals your profit margin before ad spend. Enter your per-unit numbers above.
Your ceiling is your margin.
ACOS (Advertising Cost of Sales) is ad spend divided by ad sales. Your break-even ACOS is simply your profit margin before ad spend: spend exactly that percentage and you make zero on the sale. Spend less, you profit. Spend more, you lose.
The formula
Profit before ads = price minus COGS minus Amazon fees. Break-even ACOS = that profit divided by price. To hit a target net margin, your max ACOS = break-even ACOS minus your target margin. Need your per-unit fee number? Get it from the FBA profit calculator.
ACOS vs TACOS
ACOS measures a single campaign. TACOS (Total ACOS) is ad spend divided by total sales, organic plus paid. A healthy TACOS sits around 10 to 15%, and a falling TACOS while sales grow means your ads are lifting organic rank too.
From margin to max bid in one pass.
Take a product that sells at $24.99 with a $6.00 landed cost and $9.20 in total Amazon fees. Profit before ads is $9.79, so break-even ACOS is 9.79 divided by 24.99, which is 39.2%. Any campaign running under 39.2% makes money on the sale; anything above it is buying revenue at a loss.
Now hold a 15% net margin target. Max ACOS drops to 39.2 minus 15, so 24.2%. A campaign spending $300 to drive $1,000 in ad sales runs a 30% ACOS: profitable against break-even, but 5.8 points past target, so you would trim bids or fix the listing before scaling it.
How is break-even ACOS calculated?
Break-even ACOS equals your profit margin before advertising. Take price minus product cost minus Amazon fees, divide by price, and that percentage is the ACOS at which ad profit is zero.
What is a good ACOS on Amazon?
It depends on stage and margin. New products often run 40 to 50% to gain traction; established products target 15 to 25%. The real ceiling is your break-even ACOS, which this tool calculates.
What is the difference between ACOS and TACOS?
ACOS is ad spend over ad-attributed sales (campaign efficiency). TACOS is ad spend over total sales (the whole business). A healthy, falling TACOS signals your ads are driving organic growth.
Is a high ACOS always bad?
No. During a launch, a high ACOS that builds rank and reviews can be a smart investment. It only becomes a problem when it sits above your break-even ACOS on an established product.
Should I set one ACOS target for the whole account?
No. Break-even ACOS moves with each product's price, cost and fees, so a single blended target hides losers inside winners. Set targets per product or per campaign, then judge every campaign against its own ceiling.
How often should I recalculate break-even ACOS?
Any time price, product cost or fees change, and at least quarterly. Fee updates and rising freight quietly move the ceiling, and a target set on last year's numbers can leave you scaling unprofitable spend.
Estimates for planning only. Results depend on the accuracy of your per-unit cost and fee inputs.
Want us to fix what the numbers reveal? Let’s grow your brand.
Get my free audit ↗Book a free 3-day audit. We pull your account live, find your three biggest leaks, and hand you a 90-day plan to keep.