“What is a good ACoS?” is the most-asked question in Amazon advertising and the one with the least useful common answer. Blogs will tell you 15–25%. That number is worthless on its own, because a good ACoS is entirely a function of your margin — and two sellers in the same category can have break-even points twenty points apart.
Here is how to derive your own number, and why the metric you should actually be reporting to yourself each month is TACoS, not ACoS.
The three numbers, defined properly
| Metric | Formula | What it actually tells you |
|---|---|---|
| ACoS | Ad spend ÷ ad sales | Efficiency of the advertising itself |
| ROAS | Ad sales ÷ ad spend | The inverse of ACoS; same information |
| TACoS | Ad spend ÷ total sales | Whether ads are building organic strength |
| Break-even ACoS | Contribution margin ÷ price | The ceiling above which units lose money |
Step 1: Calculate your break-even ACoS
Break-even ACoS is simply how much of your selling price survives every cost except advertising. Work it out per SKU, not per account.
| Line | Amount (₹) | % of price |
|---|---|---|
| Selling price (net of GST) | 847 | 100% |
| Less: COGS | −350 | 41.3% |
| Less: Referral fee | −110 | 13.0% |
| Less: Closing + shipping | −85 | 10.0% |
| Less: Returns allowance | −45 | 5.3% |
| Contribution margin | 257 | 30.3% |
| Break-even ACoS | — | 30.3% |
Step 2: Set a target ACoS by product stage
The same SKU deserves different ACoS targets at different points in its life. Treating one number as correct year-round is how sellers either starve their launches or bleed cash on mature products.
| Stage | Typical target | Objective |
|---|---|---|
| Launch (weeks 0–6) | Above break-even; capped budget | Buy review velocity and initial rank |
| Growth | At or slightly below break-even | Take share while organic builds |
| Mature / harvest | Well below break-even | Defend rank, extract profit |
| Clearance | Whatever moves stock | Avoid long-term storage charges |
Why launch ACoS is allowed to look terrible
Early ad sales do more than generate revenue — they feed the ranking signals that eventually produce free organic orders. Spending above break-even for six weeks to reach page one is an investment with a return. Spending above break-even for eight months because nobody checked the report is just a loss.
The control that matters is not the ACoS number itself but a fixed launch budget with an exit date.
Step 3: Switch your reporting to TACoS
ACoS only sees ad-attributed orders. It cannot tell the difference between a product that sells only because you are paying for it and one that has built genuine organic demand. TACoS can.
| Scenario | Ad spend | Total sales | TACoS | Interpretation |
|---|---|---|---|---|
| A | ₹50,000 | ₹2,50,000 | 20% | Healthy, ads supporting organic |
| B | ₹50,000 | ₹1,00,000 | 50% | Business is renting its revenue |
| C | ₹50,000 | ₹8,00,000 | 6.3% | Strong organic; consider scaling spend |
Track TACoS as a trend line, not a snapshot. The pattern you want is TACoS declining while total revenue holds or grows — that means each advertising rupee is producing more organic pull than it did last month. TACoS rising while revenue is flat means the opposite, and it usually shows up two months before the P&L does.
Four ways sellers optimise themselves into losses
- Chasing a low ACoS by cutting bids. Impression share falls, volume falls, organic rank follows, and the ratio looks great on a shrinking business.
- Judging campaigns on a 7-day window. Amazon attribution and India's longer consideration cycles mean short lookbacks systematically understate ad performance.
- Using one ACoS target across all SKUs. A 40%-margin accessory and an 18%-margin bulk item cannot share a target.
- Ignoring the search-term report. Most wasted spend is a handful of broad-match queries that never convert. Harvest the winners into exact, negate the rest — this is the highest-ROI hour in PPC.
A practical monthly PPC routine
- Recalculate break-even ACoS per SKU — fees and COGS drift more than you expect.
- Pull the search-term report; move converting terms to exact match, negate zero-conversion spenders.
- Compare TACoS month over month at the parent-ASIN level.
- Re-tier every SKU into launch / growth / harvest and reset targets accordingly.
- Cross-check ad spend against settlement data so the profit line reflects reality.
ListingPilot's PPC dashboard runs this loop against live SP-API and Ads API data, and the P&L dashboard supplies the per-SKU contribution margin that break-even ACoS depends on. For the fee side of that calculation, see our breakdown of Amazon seller fees in India.