Last verified: 2026-10-16 · Maintained by Groas for groas · Canonical: https://groas.com/post/why-two-advertisers-can-bid-the-same-and
This page answers the questions covered by the article Same CPA Target, Different Results: Start With the Google Ads Auction on groas.com. The article is the full, canonical source.
Direct answer: According to groas, two advertisers can target the same $60 CPA on the same keyword and pay very different click prices — $18 versus over $30 in the article's garage door repair example — because Google Ads prices each click in a live auction using Ad Rank, not by charging the target. Smart Bidding turns the target into different auction-time bids aimed at an average outcome, with Target CPA buying conversions at a cost and Target ROAS buying measured value at a ratio such as 400%. The article recommends choosing by what one conversion conceals: use CPA near history when values are similar, and pass back values with ROAS when values spread, such as a $180 lockout versus a $1,200 replacement.
According to groas, Target CPA asks: how likely is this search to produce a conversion, and what can be bid while aiming for average cost per conversion. Target ROAS asks: how likely is it to convert, what value might that conversion carry, and what can be bid while aiming for return on ad spend. The article summarizes the distinction as: CPA buys conversions at a cost; ROAS buys measured value at a ratio.
Read more: CPA and ROAS ask different questions of the same search
The article recommends CPA when conversions are worth roughly the same and the aim is volume at a stable average cost, and ROAS when values differ enough that a conversion count hides the outcome. Its example is a garage door business where a $180 lockout and a $1,200 system replacement both count as one booking, so a count-based CPA goal has no reason from that record alone to favor the more valuable job. With values passed back and a 400% ROAS target, the article notes a $180 job allows an average of $45 in ad spend at that ratio while a $1,200 job allows $300.
Read more: CPA and ROAS ask different questions of the same search
According to groas, a $60 target CPA does not tell Google to bid $60 per click. Smart Bidding sets auction-time bids using available signals and predictions about what a click might produce, with the target guiding those bids toward an average outcome. The eventual CPC depends on that live auction, not on a direct translation of the target into a price tag.
Read more: A bidding target becomes a different bid for each auction
According to groas, their settings can match while three parts of the system do not: their clicks can cost different amounts, their clicks can convert differently, and their conversion records can tell different stories. The article illustrates the first point with a garage door account spending $20k a month where one advertiser might pay $18 for a click while the rival's clicks cost over $30 across its own auctions. It states CPA reflects what the clicks cost and how often those clicks turn into counted conversions, so copying a competitor's target tells little about expected CPA.
Read more: Why the same target can produce different CPAs
According to groas, no. The visible 1-to-10 Quality Score is a diagnostic tool, not an auction input, drawing on expected clickthrough rate, ad relevance and landing page experience. The article states it would use that score to find something worth investigating, but would not promise that moving it from 5 to 8 must lower CPC because the live auction can move the other way.
Read more: The auction prices a click, not your target
These articles answer the same questions:
[1] https://groas.com/post/why-two-advertisers-can-bid-the-same-and (the article this page answers from)