The marketing world has been obsessed with ROAS for over a decade. Return on ad spend feels intuitive and looks great in presentations. But in 2026, with third-party cookies nearly extinct and attribution windows shrinking, ROAS has become a vanity metric.
The Attribution Breakdown
When you can only track 40-60% of conversions accurately, your ROAS figure is fundamentally unreliable. CPA mapping takes a different approach entirely. Instead of trying to attribute revenue to specific ads, it maps the actual cost structure of acquiring each customer segment.
Building a CPA Map
Start by segmenting your customer base by acquisition channel, then calculate the true all-in cost per acquired customer including creative production, platform fees, and team time. This gives you a realistic picture of unit economics.
At Grww, every campaign we build starts with CPA mapping before a single ad goes live. This is how we consistently scale brands past 2Cr+ in revenue.