CPA Is the True Performance Metric

ROAS measures return on ad spend. CPA measures what it costs to acquire each new customer. A business can have excellent ROAS and still be unprofitable if the acquisition cost exceeds customer lifetime value. CPA optimization requires understanding the full economic unit, not just the campaign dashboard.

CPA Optimization Levers

  • Conversion rate optimization on landing pages (often the highest-impact lever)
  • Audience quality improvement — better targeting reduces wasted spend
  • Creative performance — CTR improvement directly reduces CPA
  • Attribution model accuracy — measuring the right conversion events at the right windows