Performance Marketing Metrics That Actually Matter
The metrics that matter in performance marketing are the ones that change a decision: ROAS, CPA, MER, contribution margin and conversion rate. Everything else, impressions, reach, likes, is context at best and distraction at worst. If a number does not change what you do next, stop reporting it.
The five numbers worth watching
ROAS (return on ad spend) tells you revenue per unit of spend at the campaign or channel level. It is the day-to-day steering metric. CPA (cost per acquisition) tells you what a customer or lead costs, which matters most when margins are tight. MER (marketing efficiency ratio), total revenue divided by total marketing spend, is the founder’s metric: it shows whether the whole machine is profitable, not just one campaign.
Add conversion rate to see whether the site is doing its job, and contribution margin to make sure you are buying profit, not just revenue. A campaign with great ROAS on low-margin products can still lose money.
Why platform ROAS lies (a little)
The ROAS inside Meta or Google is reported by the platform that wants more budget. Attribution overlap, view-through credit and last-click bias all inflate it. That is why MER matters: it is measured from your real revenue and total spend, so it cannot be gamed by attribution settings. A healthy pattern is strong platform ROAS and a MER that confirms blended profitability. When platform ROAS rises but MER does not, you are buying customers you would have won anyway.
The vanity metrics to ignore
Impressions, reach, follower count and “engagement” feel good and decide nothing. They belong in awareness reporting, not in a growth dashboard. The test is simple: would this number make you increase, hold or cut spend? If not, it is vanity. For what to do when the real numbers slip, see 5 things to check when ROAS drops.
This is also where channels connect. Good performance marketing is wasted if the website converts poorly, so conversion rate and ad metrics have to be read together, not in separate reports.
Frequently asked questions
What is a good ROAS? It depends entirely on your margin. A 3x ROAS is excellent for low-margin retail and unprofitable for some products. Set the target from contribution margin, not a benchmark.
ROAS or MER, which should I track? Both. ROAS steers campaigns day to day; MER tells you if the whole operation is profitable. Founders should watch MER above all.
How often should I review these? Weekly for ROAS and CPA at the campaign level, monthly for MER and contribution margin at the business level.
This article is part of our guide to working with a Turkey-based agency.
Last updated: June 2026. If you want reporting that talks return instead of impressions, start with a free analysis.