Amazon ACoS, Explained: Find Your Break-Even and Stop Guessing

What ACoS measures

ACoS (Advertising Cost of Sale) is the share of ad-attributed sales you spent on ads to get them.

ACoS = Ad spend ÷ Ad-attributed sales × 100

Spend $500 on Sponsored Products and they’re credited with $2,000 in sales: your ACoS is 25%.

Two things ACoS does not tell you:

• Whether you made money. A 25% ACoS is excellent on a product with a 45% margin and a loss on one with a 20% margin.
• What ads did for the rest of the business. Ads that push a product up the organic rankings lift sales ACoS never sees. That’s what TACoS is for (below).

Your break-even ACoS

The only ACoS target that means anything is one derived from your own numbers. Start with the margin a sale leaves you before advertising:

Pre-ad margin = (Price − Product cost − Amazon referral fee − FBA fee − Other per-unit costs) ÷ Price
Break-even ACoS = Pre-ad margin

Example. A product sells for $30.

Per unit	Amount
Price	$30.00
Landed product cost	−$7.50
Referral fee (15% here; check your category)	−$4.50
FBA fulfilment fee (use your actual fee)	−$5.00
Returns and storage allowance	−$1.00
Left before ads	$12.00

$12 ÷ $30 = 40% pre-ad margin, so the break-even ACoS is 40%. At 40% every ad-driven sale earns exactly nothing; below it, ads are profitable; above it, each ad sale loses money.

That’s a ceiling, not a target. Decide how much of the $12 you want to keep:

Goal for this product	Target ACoS (example)
Launch: buy ranking and reviews, accept ~break-even	up to 40%
Grow: keep roughly a third of the margin	~27%
Harvest: mature product, protect profit	~15–20%

Do this per product. A catalogue-wide ACoS target averages a 60%-margin product with a 20%-margin one and fits neither.

Read ACoS next to TACoS

TACoS = Ad spend ÷ Total sales (ads + organic) × 100

TACoS tells you whether advertising is building the business or just renting it:

• ACoS steady, TACoS falling: ads are lifting organic sales. Healthy.
• ACoS steady, TACoS rising: sales are becoming more ad-dependent. Look at rankings, reviews and price.
• ACoS falling, TACoS flat: you may have cut spend on terms that were feeding organic rank. Watch organic sales over the next few weeks.

Where wasted ACoS usually hides

1. Search terms that click and never convert

Your search term report shows what shoppers actually typed. Sort by spend and look for terms with plenty of clicks and no orders.

A useful rule: if your conversion rate is 10%, you’d expect roughly one order every 10 clicks. A term at 20+ clicks with zero orders is strong evidence, so add it as a negative exact keyword in that campaign. Set the threshold from your conversion rate, not a fixed number.

2. Converting terms stuck in broad or auto campaigns

When a search term converts well in an auto or broad campaign, add it as an exact keyword in a manual campaign where you control its bid, and negate it in the source campaign so the two don’t compete.

3. Bids set once and forgotten

Raise bids gradually on terms beating target ACoS with room to scale; lower them on terms above target before pausing outright. Review weekly, not daily: a day’s data is noise.

4. Your own brand terms, undifferentiated

Branded searches convert cheaply and make a campaign’s ACoS look better than your prospecting really is. Keep brand terms in their own campaign so you can judge both honestly.

5. The listing, not the ad

Every conversion-rate point you add lowers ACoS on every term at once. If a term gets clicks but the listing doesn’t convert, the fix is the main image, price or first bullet, not the bid.

Common mistakes

• Copying a benchmark. “Good ACoS is 25%” means nothing without your margin.
• Judging too early. A new keyword needs enough clicks to show a pattern before you pause it.
• Ignoring attribution windows. Sponsored Products credits sales for a period after the click, so the last few days of any report are still filling in.
• Treating a low ACoS as the goal. You can hit 5% ACoS by barely advertising. The goal is profit dollars.

Next steps

1. Work out the break-even ACoS for your top five products with the PPC calculator.
2. Pick a goal (launch, grow or harvest) for each and set a target below break-even.
3. Pull the last 30 days of search terms and negate the clear wasters.
4. Add TACoS to your weekly review.

If reviewing search terms every week is the part that never happens, Hive Mind Ad Optimizer does that review for Sponsored Products every day. It proposes each negative keyword with the clicks, spend and reasoning behind it, and changes nothing in your account until you choose to let it act.