Target CPA vs. Target ROAS
Choose Target CPA when every conversion is worth roughly the same — a lead is a lead. Choose Target ROAS when conversions carry different values and you can pass them to the platform: a €200 basket and a €2,000 basket don't deserve the same bid. The practical rule: without conversion values sent correctly, tROAS has nothing to work with.
tCPA optimizes cost per conversion; tROAS optimizes value returned per unit spent — and requires real conversion values.
tCPA
Target CPA (tCPA)Target cost-per-action. A variant of maximize conversions with a target cost per conversion. Still volume-driven, but with an efficiency constraint.
Lead gen, services, B2B — conversions are homogeneous in value, or real value is only decided in the CRM, months later.
tROAS
Target ROAS (tROAS)Target return on ad spend. You tell the system how much value you want back per unit spent, and the AI bids aggressively on searches with high predicted value and pulls back on weak ones. Mechanically: max bid = predicted conversion value ÷ ROAS target.
E-commerce with varied baskets or different margins per category, and value tracking (or value-based bidding) implemented correctly.
This comparison is part of the Atlas — Websem's reference of AI search, Google Ads, tracking and chatbot terms. 129 terms, each with its own definition.