What Is ACoS and What Is a Good ACoS? Its Link to ROAS and the Break-Even Math

Every seller who runs ads wrestles with the same two questions: “Is this ad making money?” and “How much spend is too much?” ACoS and ROAS are exactly the metrics that measure those two questions — one foregrounds the spend, the other the return, but they are two faces of the same truth. In this article we separate ACoS and ROAS without mixing up their definitions, show the inverse relationship with an example, and tie the real question — “what is a good ACoS?” — to a single-sentence rule: your break-even ACoS equals your net profit margin.

What is ACoS?

ACoS (Advertising Cost of Sales) is the ratio that shows how many liras of every 100 TL of ad-driven revenue go to advertising. The formula is simple:

• ACoS = ad spend ÷ ad-attributed revenue (as a percentage)

If you spend 1,000 TL and generate 5,000 TL of ad revenue, ACoS = 1,000 ÷ 5,000 = 20%. That is, 20 TL of every 100 TL of ad revenue is the advertising cost. The lower the ACoS, the more “efficient” the ad; the higher it is, the more “expensive.” In the Amazon world this term is the standard; say “ACoS” and everyone knows this ratio.

What is ROAS and how does it relate to ACoS?

ROAS (Return on Ad Spend) flips the same calculation: it tells you how many TL of revenue each 1 TL of ads brings.

• ROAS = ad-attributed revenue ÷ ad spend (as a multiple, e.g. 5x)

In the same example, ROAS = 5,000 ÷ 1,000 = 5. ACoS and ROAS are inverses of each other; one puts the denominator first, the other the numerator. There is a single formula between them:

• ACoS = 1 ÷ ROAS  ·  ROAS = 1 ÷ ACoS
• ROAS 5 → ACoS 20%
• ROAS 4 → ACoS 25%
• ROAS 2 → ACoS 50%
• ROAS 1 → ACoS 100% (all revenue goes to ads)

So they are not different numbers but two representations of the same one. The Trendyol panel writes the return as ROAS, the Amazon panel writes the cost as ACoS — most of the confusion comes from here. Instead of converting between the two by hand, enter your spend and revenue into the ACoS calculator and see both ACoS and ROAS on the same screen. If you prefer to work directly with ROAS on the Trendyol side, the Trendyol ROAS calculator does the same job from the return angle.

Numeric example: one campaign, two metrics

In a product campaign you spent 2,000 TL on ads in a month, and the revenue attributed to that campaign was 8,000 TL. Both metrics come from the same data:

• ACoS = 2,000 ÷ 8,000 = 25%
• ROAS = 8,000 ÷ 2,000 = 4
• Check: 1 ÷ 4 = 25% ✓

You cannot say on its own whether this 25% is good or bad — because a good ACoS depends on your margin. That is exactly why the next section is the heart of the whole article.

Break-even ACoS = net profit margin (the core rule)

The only correct answer to “what is a good ACoS?” is not a number but a threshold: the break-even ACoS. This threshold is identical to your net profit margin before deducting the ad cost. The logic: when you sell the item, after product cost, commission, shipping, service fees, and withholding, you keep a profit equal to some percentage of the revenue. Advertising also eats a percentage of the revenue. The moment the percentage the ad eats equals the percentage of your profit, you are at break-even.

Short rule: Break-even ACoS = net profit margin %. If your ACoS is below this threshold, every advertised sale makes a profit; if it is equal, you break even; if it is above, you lose money per sale. In ROAS terms, the same thing: break-even ROAS = 1 ÷ net margin.

Break-even ACoS example

Say your net margin after all of the product’s costs is 25% (i.e. 25 TL of profit on 100 TL of revenue). Then break-even ACoS = 25%. Let’s look at three scenarios:

• ACoS 15% (ROAS ~6.7): 15 TL of ads on 100 TL of revenue. 25 − 15 = 10 TL net profit. Harvest mode — you want to scale this campaign.
• ACoS 25% (ROAS 4): 25 TL of ads on 100 TL of revenue. 25 − 25 = 0 TL. Break-even; you sell the item at no loss but no profit.
• ACoS 35% (ROAS ~2.9): 35 TL of ads on 100 TL of revenue. 25 − 35 = −10 TL loss. Revenue may look like it is rising, yet every sale takes money out of your pocket.

Note: a “sounds good” number like ROAS 4 means only break-even if your margin is 25% — not profit. That is why setting a target without knowing the break-even threshold is dangerous. Use the profit margin calculator to clarify your margin, and the break-even point calculator to see at what revenue you cover your costs; the resulting net margin percentage is directly your break-even ACoS.

What is a good ACoS? Decide by goal

Blanket statements like “a good ACoS in the industry is 15%” are misleading, because on a product with a 10% margin a 15% ACoS is a loss, while on a product with a 40% margin a 30% ACoS is plenty of profit. The right question is not “what is the ideal number?” but “what is my goal?” A decision framework:

1. If you want profit today: keep your target ACoS clearly below break-even (e.g. if break-even is 25%, target 15–18%). The gap is your profit per sale.
2. If you want to grow at break-even: keep ACoS near break-even; you won’t profit, but you gain revenue, ranking, and visibility. It should be a deliberate choice, not an accident.
3. If you are investing (launch): you temporarily accept going above break-even — details below. This is not a “loss” but a measured marketing budget.

In short, the ideal ACoS is a personal threshold defined by your net margin, not a one-size-fits-all number. The higher your margin, the higher your ideal ACoS; on a cheap, low-margin product your advertising room shrinks.

The difference between Amazon (ACoS) and Trendyol (ROAS) is really a language difference

Sellers who sell across multiple marketplaces usually get confused right here: the same ad performance speaks in two different “languages” in the two panels.

• Amazon reports the metric as ACoS (and TACoS for the total); the goal is “lower your ACoS.”
• Trendyol mostly shows performance as ROAS in its ad panel; the goal is “raise your ROAS.”

Both lead to the same decision. On Amazon you ask “is my ACoS below break-even?”; on Trendyol, “is my ROAS above break-even ROAS?” The math does not change: ACoS 25% = ROAS 4. If you want to deepen the break-even ROAS and target ROAS setup on the Trendyol side, the article what should your ROAS be on Trendyol explains this logic from the ROAS angle; for quick conversion between ACoS and ROAS, again the ACoS calculator does the job.

TACoS: the ad’s effect on the whole business

ACoS measures only ad-attributed revenue; it ignores organic (non-ad) sales. Yet a good ad campaign lifts the product’s ranking and feeds organic sales too. The metric that captures this is TACoS (Total ACoS):

• TACoS = total ad spend ÷ total revenue (ad + organic)

With ACoS holding steady, a falling TACoS over time is a healthy sign: it means ads are growing your brand and the organic share of sales is rising. If TACoS is climbing, your business is becoming increasingly dependent on ads. Track daily campaign optimization with ACoS, and long-term health with TACoS.

Why does a high ACoS make sense during a product launch?

If the rule is “ACoS should be below break-even,” why deliberately go above it at launch? Because a new product has no sales history, reviews, or ranking yet; the marketplace algorithm needs data to make it visible. In the early launch period:

• You accept a high ACoS as a temporary visibility and momentum investment.
• The aim is not profit; it is to accumulate the first sales, reviews, and search ranking.
• As the product settles into the ranking organically, dependence on ads falls; you gradually pull ACoS below break-even.

This should be a deliberate strategy: set a budget and an end date up front. The difference between “the product isn’t selling but I left the ad on” and “I’m investing for 6 weeks to settle the product into the ranking” is whether there is a plan. If the loss period is open-ended, it is not an investment but a leak.

Tie the profitability decision to a system

The entire ad decision comes down to two numbers: your break-even ACoS (i.e. your net margin) and your actual ACoS. You cannot set a target for the second without knowing the first. Run it in order:

1. Work out the product’s real net margin — that is your break-even ACoS. Instead of building it by hand, find it with the profit margin calculator by subtracting commission, shipping, and costs.
2. Measure the campaign’s ACoS (or ROAS) and compare it against your break-even threshold; the ACoS calculator gives you both on one screen.
3. If ACoS is below your threshold, scale up; if above, either fix the price/cost side or (if it is not a launch) cut back.

Verimle, once you track your sales, reads the real deductions of every order (commission, commission VAT, shipping, service fees, withholding) from the breakdown and derives net margin per product — that is, your break-even ACoS. This way you place your ad spend on top of your real margin; you decide with your own product’s threshold, not with blanket assumptions like “ROAS 4 is good.” You see whether scaling ads is truly profit or a masked loss by tracking the deduction, not by guessing at the table.

One final note: the ACoS/ROAS thresholds and numeric examples here are illustrative; the ideal ACoS is not a single right value that fits everyone — it varies with your product’s profit margin, category, and campaign goal. To see your own result, enter your spend and revenue figures into the ACoS calculator and compute your ACoS and ROAS threshold with your own data. This guide was last reviewed on July 18, 2026.