Cost per click

Cost per click (CPC), also called pay per click (PPC) when used as a pricing model, is an online advertising model and metric in which an advertiser pays a fee each time a user clicks an advertisement. It is calculated by dividing total advertising cost by the number of clicks received. It is used to budget, price, and compare digital advertising campaigns.

CPC is one of several pricing models in digital advertising, alongside cost per thousand impressions (CPM) and cost per acquisition (CPA). It is widely used in search advertising, social media advertising, and display networks. Because charges occur only when a click is recorded, the model ties expenditure to a measurable user action rather than to exposure alone.

Field	Value
Type	Advertising pricing model and performance metric
Also known as	Pay per click (PPC); cost per click
Basic formula	Total cost ÷ number of clicks
Commonly used in	Search, social, display, and shopping ads
Related metrics	CPM, CPA, CTR, ROAS
Popularized	Late 1990s (search advertising)

Calculation

The basic formula is:

CPC = total ad cost ÷ total clicks

For example, a campaign that spends 500 currency units and receives 250 clicks has an average CPC of 2.00. The figure is expressed in the currency of the advertising account.

Platforms distinguish between several related values:

• Maximum CPC (max CPC): the highest amount an advertiser is willing to pay per click, set manually or by an automated bidding system.
• Actual CPC: the amount charged for an individual click, which is often lower than the maximum.
• Average CPC: total cost divided by total clicks over a reporting period.

Note: A "click" as counted by an advertising platform may differ from a "visit" recorded by a website analytics tool. Filtering of invalid clicks, redirects, and users leaving before a page loads can produce differences between the two figures.

How CPC is determined

Auction-based pricing

On major platforms, CPC is set through an auction that runs each time an ad opportunity arises, such as a search query. Advertisers submit bids, and the platform ranks eligible ads using both the bid and estimates of ad quality. Google Ads, for instance, describes a metric called Ad Rank that combines bid, expected click-through rate, ad relevance, landing page experience, and other factors.

Under this approach, an advertiser with a lower bid can outrank a competitor if its ad is judged more relevant. Google Ads documentation states that the amount charged is typically the minimum needed to keep the ad's position, so actual CPC is often below the maximum bid. Platforms differ in their auction rules, and details change over time.

Academic background

Economists have studied these mechanisms, often described as generalized second-price auctions. Papers by Benjamin Edelman, Michael Ostrovsky, and Michael Schwarz (2007) and by Hal Varian (2007) analyzed the properties of position auctions used in search advertising. Real-world systems include quality adjustments and other rules beyond the simplified models in these studies.

Factors influencing CPC

Observed CPC varies widely. Commonly cited influences include:

1. Competition: keywords or audiences that many advertisers target tend to command higher prices.
2. Industry: sectors such as insurance, legal services, and finance are frequently reported to have high average CPCs, though figures vary by year and data source.
3. Ad quality and relevance: higher estimated relevance can lower the price needed for a given position.
4. Geography, device, and time: prices may differ by location, device type, season, or time of day.
5. Platform: search, social, and display networks report different typical CPC ranges.

Published industry benchmarks are compiled by advertising agencies and software vendors, and methodologies differ. Benchmarks are therefore best treated as indicative rather than definitive.

Bidding strategies

Advertisers can set CPC bids in several ways.

• Manual CPC bidding: the advertiser sets bids directly for keywords, ad groups, or audiences.
• Automated bidding: the platform adjusts bids using machine learning to pursue a stated goal, such as maximizing clicks or reaching a target cost per conversion.
• Enhanced CPC: a hybrid in which manual bids are adjusted upward or downward based on the estimated likelihood of conversion. Google announced in 2024 that it would phase out this option for some campaign types, so its availability depends on the platform and date.

Automated strategies may cause the actual CPC to differ from what an advertiser might set manually, because the system optimizes toward a goal rather than a fixed price per click.

Comparison with other pricing models

Model	Advertiser pays for	Typical use
CPC	Each click	Search ads, traffic-focused campaigns
CPM (cost per mille)	Every 1,000 impressions	Brand awareness, display, video
CPA (cost per acquisition)	A defined action, such as a purchase or sign-up	Performance and affiliate marketing
CPV (cost per view)	A video view meeting a threshold	Video advertising

CPC is often confused with click-through rate (CTR), which is the percentage of impressions that result in clicks (clicks ÷ impressions). CTR measures response to an ad, whereas CPC measures cost. A low CPC does not by itself indicate a profitable campaign, since the value of each click depends on what users do afterward. Metrics such as conversion rate, cost per acquisition, and return on ad spend (ROAS) are used to assess that outcome.

History

Pay-per-click pricing for search results is commonly credited to Bill Gross and his company GoTo.com, later renamed Overture and acquired by Yahoo in 2003. GoTo launched its model around 1998, letting advertisers bid for placement in search results and pay when users clicked.

Google introduced AdWords in October 2000, initially charging by impressions. It moved to CPC pricing in February 2002 and incorporated click-through rate into ad ranking, an approach that influenced later systems. Microsoft Advertising, formerly Bing Ads, and social platforms such as Facebook and LinkedIn later adopted CPC options. Jansen and Mullen (2008) provide a scholarly overview of sponsored search history.

Exact launch dates and attributions vary slightly between sources, so the years above should be read as commonly cited approximations for early events.

Criticism and controversy

Click fraud

Click fraud refers to clicks generated with no genuine interest in the advertiser's offering, whether by automated bots, competitors, or publishers seeking revenue. Platforms state that they filter invalid clicks and credit affected advertisers. The scale of the problem is disputed: estimates come from security vendors and advertisers and are difficult to verify independently. In 2006, Google agreed to a reported $90 million settlement in a US class action (Lane's Gifts and Collectibles v. Google) alleging inadequate handling of invalid clicks, without admitting wrongdoing.

Transparency concerns

Some advertisers and researchers have questioned how much control advertisers retain over pricing given automated bidding and auction rules the platforms do not fully disclose. Platforms respond that auction opacity protects against manipulation. The debate remains unresolved.

Current status

CPC remains a core pricing model for search and social advertising. Advertisers increasingly combine it with automated bidding and conversion-based goals, and platform features and metric definitions continue to change.