ScaleyThe PPC Model: How a Click Gets Its Price
What the pay-per-click model is, how Google Ads decides what one click costs, and why you often pay less than your bid.
Written and reviewed by Christopher Krassnig
Published Last checked
The PPC (pay-per-click) model is a way to buy ads where you pay only when someone clicks. Google Ads calls it cost-per-click (CPC) bidding. You set a max CPC, the most you will pay for 1 click, and Google's auction usually charges you less: just enough to beat the ad ranked below yours.
Also called: PPC, cost-per-click (CPC) model, pay per click advertising
PPC Model, the Advertising One
Quick note first. In economics class, "PPC model" means the production possibilities curve. This page is about the other PPC: pay-per-click advertising, the model Google Ads runs on. If you came for the economics graph, a textbook is the right place.
How the Pay-per-Click Model Works in Google Ads
Google says cost-per-click bidding "means that you pay for each click on your ads", and that "CPC pricing is sometimes known as pay-per-click (PPC)."
You set a max CPC, the highest amount you are willing to pay for one click. Google says a click "won't cost you more than the maximum CPC bid amount that you set", unless you use bid adjustments or certain automated bidding. You can set bids yourself (manual) or let Google set them (automatic).
An impression, where your ad shows and nobody clicks, costs nothing under this model. That is the big difference from cost per impression (CPM) buying, where you pay for views.
Max CPC vs Actual CPC
Your actual CPC is what you really pay. Google says you "only pay what's minimally required to clear the Ad Rank thresholds and beat the Ad Rank of the competitor immediately below you." If nobody is below you, you pay the reserve price.
Google's own simplified example: 5 advertisers have Ad Ranks of 80, 50, 30, 10 and 5, and showing above the results needs at least 40. Only the first two show there. The advertiser at 80 pays just enough to beat 50, rounded up to the nearest billable unit ($0.01 in the US). The one at 50 pays just enough to beat the minimum of 40.
So your bid is not your price. Your Ad Rank, and the Ad Rank of the ad under you, set your price.
What Decides Who Wins the Click
Google lists 6 main auction factors:
- Your bid.
- The quality of your ads and landing page (summed up in your Quality Score).
- The expected impact of your ad assets and other ad formats.
- Your Ad Rank thresholds, the minimum quality to show in a spot.
- The context of the search: the words, location, device, time and more.
- How competitive the auction is.
That is why a better ad can beat a bigger bid. Google says that "even if your competition has higher bids, you can still win a higher position at a lower price by using highly relevant keywords, ads, and assets."
Example: What a Store Pays per Click
Made-up numbers, to show the method. A kitchenware store bids a max CPC of $2.00 on "cast iron skillet". Over a week its ad gets 1,000 impressions and 40 clicks, and it spends $56.
Its average actual CPC is $56 / 40 = $1.40. It never paid more than its $2.00 bid, and it paid nothing for the 960 impressions nobody clicked.
If 2 of those 40 clicks bought a $60 skillet, the store made $120 from $56 of clicks. Our CPC calculator and ROAS calculator run these sums for you.
Common Mistakes
Thinking your bid is your price
Google usually charges less than your max CPC. Your Ad Rank and the ad below you set the price.
Only raising bids to win
Ad quality and assets are auction factors too. A better ad can win a higher spot for less.
Judging PPC by clicks alone
A click is a cost, not a sale. Track conversions and what each sale cost.
Questions People Ask
Pay-per-click. You pay when someone clicks your ad, not when it shows. Google Ads calls it cost-per-click (CPC) bidding.
Google's Own Pages We Quoted
Every rule, limit and size on this page comes from these pages, read on 8 October 2026. Google changes them, so check the page itself before you act.
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