Ask which performance marketing metrics matter and most answers stop at ROAS. That is the expensive answer. ROAS does not lie; it answers a question you did not ask.
Turkish search results for this question are glossaries: CPC, CTR, conversion rate, ROAS, CPL, each defined, none connected. A glossary is not a decision tool. This piece orders the metrics by the question each one answers, and shows which one can overrule the others.
Why is ROAS not enough on its own?
ROAS measures revenue, not profit, and it measures it by the platform's own count rather than your ledger. Digital ad investment in Turkey passed 158 billion TL in 2024, 74.2% of all media spend, with 47.08% of that going to social (IAB Türkiye with Deloitte, April 2025). Most of the budget is spent where the seller also writes the report.
How do you calculate break-even ROAS?
Break-even ROAS is 1 divided by your contribution margin; at a 25% margin, anything under 4.0 loses money. Take a hypothetical brand spending 200,000 TL a month at a reported 5.0 ROAS with a 22% contribution margin. Break-even is 4.55. On paper, there is a cushion.
Why don't platform numbers match actual sales?
Every platform counts the conversions it saw, so the same order can be claimed twice. The error runs both ways. Haus reviewed 640 Meta incrementality experiments (July 2025) and found 7-day click attribution under-reported Meta's DTC impact by about 15%, while roughly 32% of Meta's impact landed in non-DTC channels. For a Turkish brand selling on Trendyol and Hepsiburada, that is revenue the pixel never sees.
What is incremental ROAS?
Incremental ROAS counts only the sales that would not have happened without the ad. In Haus's data, Meta lifted brands' primary KPI by about 19% on average, and 58% of brands saw higher incremental ROAS on manual campaigns than on Advantage+, despite Advantage+ looking better in its own reporting. Apply an illustrative 0.7 factor to our 5.0 ROAS and it becomes 3.5, below the 4.55 break-even. The celebrated campaign is losing money.
The dashboard tells you what people bought after seeing the ad. What you need is what they would not have bought without it.
Which metrics belong together?
The right set is small and self-checking:
- Break-even ROAS by product group, from contribution margin.
- MER: total revenue over total marketing spend, immune to double counting.
- Incremental ROAS, tested with holdouts at least twice a year.
- New-customer acquisition cost, separated from repeat buyers.
- Order and unit counts, because lira revenue inflates and units do not.
Google opened its Meridian marketing mix model to everyone on January 29, 2025, and added a no-code interface in February 2026. Independent budget checks have never been cheaper.
How does inflation distort the numbers?
Annual CPI in Turkey was 31.51% in August 2026 (TÜİK), so year-on-year lira comparisons mean little until deflated. A CAC that moved from 450 TL to 590 TL rose about 31%: that is inflation, not deterioration, and a 30% revenue gain with flat order counts is a price tag, not growth.
What to do on Monday
Compute contribution margin and break-even ROAS per product group. Sum last month's platform-reported conversions and compare them with your store's order count. Add MER and new-customer share to the weekly report. Then book a four-week geo or audience holdout on your largest channel, so the next budget meeting runs on your number, not the platform's.
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