What Is CPC Advertising? How Billing Works and How to Choose Between CPC and CPM
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Authors: Shusaku Yosa
When running web advertising, the first thing you decide is the "billing method." Among them, CPC advertising (cost-per-click) is widely used, especially for listing ads. In this article, we organize how CPC advertising's billing works and its calculation method, and then explain the main media, the differences from CPM and CPA, the benefits and drawbacks, and how to choose between CPC and CPM for your objective—all from a practical perspective.
CPC advertising is advertising delivered under a billing method (cost-per-click) where a cost is incurred each time the ad is "clicked." CPC stands for "Cost Per Click." As the name suggests, it represents how much it costs each time an ad is clicked once.
The key point is that no matter how many times the ad is displayed, no cost is incurred unless it is clicked. Because you are only charged when a user actually clicks the ad and visits your site, the major characteristic is that "you can spend only on users who have shown interest." It is easier to understand if you view it as the counterpart to "impression-based billing (CPM)," where you are charged only for the number of times the ad is displayed.
CPC (cost per click) is calculated by dividing the cost spent on the ad by the number of clicks. The formula is as follows.
CPC (yen) = Advertising cost ÷ Number of clicks
For example, if an ad cost of 100,000 yen results in 1,000 clicks, the CPC is "100,000 ÷ 1,000 = 100 yen." In other words, it costs 100 yen per click. Conversely, if the bid per click and the budget are set, you can also estimate roughly how many clicks you can acquire.
In many CPC ads, the actual cost per click is determined by an "auction (bidding)." Multiple advertisers bid on the same keyword or slot, and the combination of the bid amount and the ad's quality (such as the quality score) determines the placement rank and the actual cost per click. For this reason, not only raising your bid but also improving the quality of your ad is important for keeping the cost per click down.
CPC billing is adopted for ads that aim to drive inflow to a site or generate results via clicks. The most representative are search-linked listing ads (Google Ads search ads and Yahoo! search ads). In addition, social media ads (such as Meta ads and X ads) and display ads often offer the option to choose click-based billing. Listing ads in particular are a representative example with good compatibility with click-based billing, because you can deliver them in line with keywords searched by users with high interest.
In addition to CPC, web advertising billing methods include CPM and CPA. "Where the billing occurs" differs for each.
The further the billing point advances along "display → click → result," the closer the user's behavior gets to the goal. CPC sits in the middle, and because you can spend only on "users who clicked out of interest," it suits situations where you want to drive site inflow efficiently. For the detailed differences from CPM and CPA and how to use them properly, please also refer to the related articles.
As a supplementary note, CPC, CPM, and CPA are not only "billing methods" but also used as "metrics" for measuring advertising effectiveness. For example, even for an ad delivered under CPM billing, it is common to calculate how much it ultimately cost per click (CPC) to evaluate effectiveness. Keeping in mind that CPC has two faces—as a billing method and as a metric for evaluating results—helps avoid confusion.
Because CPC advertising incurs no cost unless it is clicked, you do not pay for "wasted displays" that are merely shown without leading to a click. Since you pay only for users who actually visit your site, the major advantage is that it is easy to control cost-effectiveness.
Click-based billing is easy to start with even on a small budget, and because you can gather only users who clicked onto your site, it has the characteristic of being more likely to lead to results such as purchases and inquiries after inflow. Listing ads in particular let you deliver targeting users with high purchase intent, making it easier to raise cost-effectiveness.
Because CPC billing fluctuates with the number of clicks, if clicks surge due to something like a social media spread, the billed amount can jump beyond expectations. Compared with CPM, where cost is determined by display count, monthly budgets can be harder to predict, so setting a budget cap and managing progress are important.
For popular keywords or slots with many competitors, bidding competition intensifies and the cost per click tends to surge. When the cost per click rises, the number of clicks you can acquire on the same budget decreases, which can make it harder to produce results. Efforts to keep the cost per click down through keyword selection and ad-quality improvement are required.
Because CPC billing is delivered with an emphasis on getting clicks, the display count itself is not necessarily maximized. If your objective is expanding brand awareness—"getting seen by many people even without clicks"—CPM, which can maximize the display count, is more suitable.
Whether to deliver under CPC or CPM is easier to sort out when judged from two perspectives: the "advertising objective" and "cost efficiency (click-through rate)."
First, clarify the objective of the ad. If the objective is "action or results" such as site inflow, purchases, or inquiries, CPC, which charges according to clicks, is suitable. On the other hand, if the objective is "getting seen by more people" such as new-product awareness or branding, CPM, which maximizes display count, is suitable.
From the perspective of cost efficiency, the click-through rate (CTR) is a deciding factor. As a general benchmark, CPC billing tends to keep costs down when the click-through rate is below 0.1%, and CPM billing when it is 0.1% or higher. This is because, for ads that are hard to get clicked, CPC avoids wasted display charges, while for ads that are easy to get clicked, CPM becomes cheaper per click.
The initial billing method is only a starting benchmark. Because the click-through rate and results fluctuate once you actually deliver, it is important to review while watching the operational data. For example, an adjustment such as "start by delivering under CPC, then switch to CPM once you find the click-through rate is high" is also effective. Not assuming that once decided it is fixed leads to better results.
CPC advertising is advertising under a click-based billing method that charges according to ad clicks. Since no cost is incurred unless it is clicked and you can spend only on users who have shown interest, it suits driving site inflow and acquiring results. On the other hand, you need to watch out for costs being hard to predict when clicks surge, and for the cost per click surging in slots with many competitors.
The basic way to choose between CPC and CPM is to judge on two axes: CPC if the objective is results and CPM if it is awareness, and on the cost side, using a 0.1% click-through rate as a benchmark. First, clarify the objective of your ad, deliver on a small scale to check the click-through rate, and adjust to the optimal billing method.
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