Ad Auctions: How Google and Meta Rank Ads

Updated September 19, 2026· 8 min read

An ad auction is the process a platform uses to decide which eligible ads can show, in what order, and at what price for one opportunity. Google Ads and Meta both run auctions. They publish different ranking inputs. Do not treat them as one formula.

Use auction diagnostics in the next paid search review, then write down the decision the numbers change.

How the Google Ads auction works

Google’s ad auction guide says an auction runs every time someone searches on Google or visits a site that shows Google ads. On Search, Google runs different auctions for each ad location. An ad shows once in a single location. It can show more than once across locations.

Google documents six main factors that decide which ads appear and in what order:

1. Your bid. The maximum you are willing to pay for a click. Actual cost is often less.
2. The quality of your ads and landing page. Usefulness and relevance of the ad and page, whether the page matches what the ad promised, ease of navigation, and other Search quality signals. Google summarizes a related diagnostic in Quality Score.
3. Expected impact of ad assets and other formats. Phone numbers, extra links, and similar assets can change predicted performance.
4. Ad Rank thresholds. Minimum quality bars an ad must clear to show in a given position. Top-of-page thresholds are generally higher.
5. Context of the search. Search terms, location, device, time, the nature of the query, other ads and results on the page, and other user signals.
6. Competitiveness of the auction. Similar Ad Ranks have a similar chance to win a position. A larger gap can raise both win likelihood and cost per click for the leader.

Ad Rank is calculated first for eligibility, then again for relative position. Google does not publish a numeric Ad Rank equation. If multiple keywords from the same account match the same search term, they do not bid against each other.

Quality Score is not the auction

Google’s Quality Score documentation states that Quality Score is a diagnostic tool, not a key performance indicator, and not an input in the ad auction. Auction-time quality still matters. The 1-to-10 score is a separate report card based on expected click-through rate, ad relevance, and landing page experience compared with other advertisers for exact searches of that keyword.

How the Meta ad auction works

Meta’s About ad auctions page describes a different system. Each time there is a chance to show an ad to a person, eligible ads (those whose target audience includes that person) compete.

The winner is the ad with the highest total value, subject to a price floor that can affect whether an ad shows and the price paid. Total value is a combination of three major factors:

1. Bid. What the advertiser is willing to pay for the desired outcome. Bid strategies change how that bid is expressed. They do not replace the auction.
2. Estimated action rates. The predicted probability that showing the ad leads to the advertiser’s desired outcome. Meta notes that clickbait and engagement bait do not improve performance.
3. Ad quality. Feedback from people viewing or hiding the ad, plus assessments of low-quality attributes such as withheld information, sensationalized language, and engagement bait.

Estimated action rates and ad quality together measure relevance. A more relevant ad can win against ads with higher bids. Meta does not publish a complete numeric total-value equation on that Help Center page. Do not reduce the system to a single multiply-and-add formula copied from older explainers.

Auction overlap, learning phase, and pacing are separate delivery topics. Confirm them in Ads Manager for the campaign you are actually running.

Google Ads and Meta auctions are not interchangeable

Topic	Google Ads (Search)	Meta
When it runs	Each search and each ad location	Each opportunity to show an ad to a person
Published ranking idea	Ad Rank from six factors	Total value from three factors, plus a price floor
Quality object	Auction-time ad and landing page quality; Quality Score is diagnostic only	Ad quality plus estimated action rates
Context	Query, device, location, time, other results	Audience membership and predicted action
Highest bid	Can lose to stronger quality and context	Can lose to a more relevant ad

Bidding strategy still matters because it sets the bid the auction sees. Manual CPC, Enhanced CPC, and Target ROAS change how bids move. They do not rewrite the ranking inputs above. Choose a strategy that matches the conversion data you actually have.

Frequently Asked Questions

How do ad auctions work?

When there is a chance to show an ad, the platform gathers eligible ads, scores them with its published inputs, and assigns the placement. The highest bid can lose when another ad has stronger predicted value or quality.

How does Google’s ad auction work?

Google runs an auction for each ad location on a search. Ad Rank uses six documented factors: bid, ad and landing page quality, expected asset impact, Ad Rank thresholds, search context, and auction competitiveness. Quality Score is a diagnostic, not an auction input.

How does Meta’s ad auction work?

Meta selects the ad with the highest total value, subject to a price floor. Total value combines bid, estimated action rates, and ad quality. A more relevant ad can beat a higher bid.

What factors affect a search ad’s auction-time quality?

Google describes auction-time quality through expected click-through rate, ad relevance, and landing page experience. Those signals sit inside the broader Ad Rank factors, which also include thresholds, competition, context, and assets.