Google paid search: how it works, what it costs and when SEO can replace it

Google paid search means the ads you buy in Google Ads (formerly AdWords): you pay per click to appear around the organic results, for as long as the budget runs. For a B2B acquisition manager, the useful question is less about set-up than about what each keyword costs, what it brings in and when organic search can take over. The overall trade-off is set out in our article on allocating SEO vs SEA keyword by keyword.

How Google paid search works

For every search, Google runs an auction between the advertisers whose keywords match the query. The amount you bid is not enough to win: placement and price come from Ad Rank, calculated from the bid and the quality of the ad.

The auction, Ad Rank and the actual CPC

The process runs in four stages, at the time of writing:

• Matching: Google matches the query to the keywords bought, according to the match type and the negative keywords that filter out off-target queries.
• Bidding: each eligible advertiser offers a maximum amount per click; automated bidding, now the norm, sets it query by query against a conversion goal.
• Ranking: Ad Rank combines the bid, the estimated quality and the search context to decide which ads appear, and in what order.
• Billing: you only pay per click, and the actual CPC (cost per click charged) is usually lower than the maximum bid: it is what it takes to beat the next advertiser.

Google therefore does not set the price of a keyword: it results from competition on the query and from your own quality.

Quality Score, or the quality that lowers the price

Google sums up this quality in the Quality Score, a keyword-level rating built on three components. The table places them alongside the bid and the context:

The stakes are financial: a Quality Score above seven comes with a 17% lower CPC (Odiens, 2025). Quality is therefore worked on the page and the message, which also serve organic search.

Google Ads formats at a glance

Each Google Ads format follows a different logic, query or audience, which changes how you measure its value:

• Search: responsive text ads (up to 15 headlines combined by Google) triggered by a query; the only format directly comparable with SEO.
• Performance Max: a single campaign serving across all Google inventories from a conversion goal, with little visibility into queries.
• Display: banners on partner sites, targeted by audience or context, for awareness and retargeting.
• Shopping: product ads powered by a feed, reserved for e-commerce.
• Demand Gen: visual and video ads on YouTube, Discover and Gmail, to create demand.

Only Search can be compared keyword by keyword with organic search: the rest of this article focuses on it.

What a keyword costs, from click to customer

The cost of a keyword reads on three levels: media cost (CPC multiplied by the number of clicks), cost per acquisition, then cost per customer. Only the last one tells you whether a keyword is profitable in B2B, where the sales cycle separates the form from the contract.

CPC, CPA, ROAS: what each metric tells you

Each metric answers a specific question and hides a trap worth knowing before you allocate budget:

To benchmark an account, the average Google Ads CPC on the Search Network stands at $2.69 across all industries (WordStream, 2025). This reference varies widely by sector; other market benchmarks are in our SEA statistics.

On the acquisition side, the average Search CPA reaches $48.96 (WordStream, 2025). In B2B, this benchmark says nothing on its own: a lead at that price can be very profitable if the sales conversion rate and customer value are high.

From cost per lead to payback period

A simple model takes you from media cost to a decision, keyword by keyword or by query group:

• Cost per lead: the keyword's spend divided by the number of leads it generates.
• Cost per customer: cost per lead divided by the lead-to-customer conversion rate, measured in the CRM through imported conversions.
• Payback period: cost per customer divided by the monthly margin a customer brings in.

This model puts CPC in its place: a keyword that is expensive per click can pay for itself quickly if the close rate is strong. It also prepares the trade-off with organic search, because a keyword with a high CPC and strong conversion becomes an SEO priority: that is where every position gained saves the most.

Paid and organic on the same query

On a given query, you can be present organically, in paid, or on both sides. The main risk is cannibalisation: buying a click you would have obtained for free, typically on your brand or on a keyword where you already rank first with no paid competitor. The decision is made query by query, based on organic position, CPC and search intent.

Cross-referencing organic position, CPC and intent

The table gives a default reading of keyword-level overlap; your incrementality measurements always take precedence over this grid:

Dual presence when the SERP is unstable

Being visible on both sides of the same query is not always waste. Dual presence is justified in three cases:

• An unstable SERP: rich results, AI modules or ads push the first organic result down, and position no longer guarantees the click.
• A brand under attack: competitors bid on your name and capture part of the clicks organic search used to bring you.
• A very high-value query: message control and screen coverage justify running both, provided you measure what it adds.

In each case, dual presence is validated by measuring incrementality.

Measuring the incrementality of paid search

Incrementality means the additional conversions obtained thanks to paid search, those that would not have happened without an ad. Attribution reports do not show it: they split conversions between channels without saying what would have happened otherwise.

The with / without delivery test

The protocol is simple, provided you keep the same scope from start to finish:

• Choose a scope: a homogeneous query group (the brand, an offer, a region), large enough for differences to be readable.
• Alternate periods: compare periods with and without delivery of the same length, outside seasonal peaks and offer changes.
• Look at total conversions: add paid and organic together and check whether the total drops when ads stop, rather than the split between channels.
• Cross-check sources: paid clicks and conversions in Google Ads, organic clicks and average position in Google Search Console, sessions by channel in Google Analytics 4.

If the total does not move without ads, paid search was replacing organic; if it drops, the gap measures what it adds.

Brand, the first ground for cannibalisation

Brand concentrates the risk. When you rank first organically and no competitor is bidding, a large share of paid clicks would have come for free. If competitors buy your name, switching ads off leaves them the top of the page. The no-delivery test settles it, and should be rerun whenever the competition changes.

What attribution lets you conclude, and what it does not

Last-click attribution favours end-of-journey channels, especially paid search on brand. The table separates what the data allows you to claim from what it does not prove:

Without an incrementality test, no report tells you "what triggered everything". Cookie consent also reduces the signal: an apparent drop may come from measurement, not performance.

When SEO replaces or secures paid search

SEO does not replace paid search everywhere. It takes over on "winnable" keywords, where an organic position is achievable at reasonable cost, and secures those where you already rank well.

Spotting winnable keywords

A paid keyword becomes a candidate for switching to organic when several signals converge:

• you are already on page one, or an existing page can get there with content and internal linking;
• the CPC is high and the keyword converts well, so every organic click gained saves a lot;
• organic competition remains within your reach;
• the intent is stable, which ensures the page will serve for a long time.

Conversely, keywords that are highly competitive in organic search are where the paid budget works best: that is where to concentrate it.

Ad cost equivalent

To quantify what SEO saves, you value organic clicks at the price they would cost in paid search: organic clicks on the query multiplied by the keyword's CPC. This ad cost equivalent puts a euro value on each position and makes the two levers comparable within a single budget.

It also helps manage the switch: as a page climbs, paid spend is reduced in steps, checking at each stage that total conversions hold. The before / after method by query group is detailed in the pillar article.

Turning SEA data into SEO priorities

Paid search learns fast: it reveals the queries that convert, the messages that get clicks and the recurring objections. These learnings feed the organic content plan:

• Converting search terms: they become page or section topics, with their exact wording.
• Winning ad headlines: the promises with the best CTR inspire the title tags of organic pages.
• Negative keywords: they flag intents not to target, or to address with informational content.
• High-performing landing pages: their structure (promise, proof, FAQ) can be reused for the same intent.
• Conversions imported from the CRM: they separate keywords that produce customers from those that produce forms.

The full method for this loop is set out in our article on the relationship between SEO and SEA.

AI Overviews and AI Mode: one more factor in the trade-off

At the time of writing, AI Overviews and AI Mode have been available in France since summer 2026. Most AI Overviews show no ads: the generated answer takes the top of the page, and visibility there comes from your content being cited rather than from bidding. Google is also testing ads in AI Mode.

Depending on your situation

The next step depends on where you are starting from:

• You pay for clicks on your brand: run a no-delivery test before renewing the budget.
• You are comparing paid and organic CTR: apply the equal-scope method from our article on SEA vs SEO click-through rate.
• Your conversions by channel are unclear: check the organic search / paid search split in Google Analytics 4.
• Your conversion tags are duplicated: centralise them with Google Tag Manager before any test.
• You need to split a budget between SEO and SEA: start from the query-family grid and the four ROAS in the pillar article.

To compare SEO and SEA keyword by keyword on your own data, the SEO vs SEA module of the Incremys GEO & SEO platform connects Google Ads, Google Search Console and Google Analytics 4. It calculates four ROAS (global, non-brand, brand with cannibalisation, brand without cannibalisation), expresses organic positions as ad cost equivalent and helps redirect paid budget towards keywords that are hard to win organically.

FAQ on Google paid search

Are paid search and Google Ads the same thing?

Almost. Paid search, or SEA, means buying ads on search engines in general. On Google, it runs through Google Ads, which also covers Display, Shopping, Demand Gen and Performance Max. Talking about Google paid search therefore means talking about Google Ads campaigns, first and foremost the ads on results pages.

How much does a click on Google cost?

The average Google Ads CPC on the Search Network stands at $2.69 across all industries (WordStream, 2025). This benchmark varies with the sector, competition on the query and the quality of your ad. The real price is in your account, keyword by keyword, and should be judged on cost per customer rather than per click.

Can you rank first in both paid and organic results?

Yes. Ads and organic results are ranked by two separate systems, and nothing stops you from holding both placements on the same query. The whole question is whether this dual presence adds conversions, or makes you pay for clicks organic search would have brought for free. A with / without delivery test settles it.

Does paid search improve organic rankings?

No. Google Search Central states that buying ads does not directly influence rankings in organic results. Paid search can, however, feed SEO indirectly: it reveals the queries that convert and the messages that get clicks, which you can then use in your content.

How do you know whether SEA brings additional conversions?

By comparing periods with and without delivery on the same query scope, then looking at total conversions, paid and organic added together. If the total stays stable when ads stop, paid search was replacing organic. If it drops, the gap measures what the ads add, to be weighed against their cost.

Do ads appear in AI Overviews?

Rarely, at the time of writing: most AI Overviews show no ads, and ads remain placed around the generated answer. Google is testing ads in AI Mode. To appear in the answer itself, you need to be cited as a source, which is a matter of SEO and GEO.

Should you bid on your own brand?

Only if a test justifies it. When you rank first organically and no competitor buys your name, brand ads mostly capture clicks you would have had for free. When competitors bid on your brand, a defensive presence protects the top of the page. The no-delivery test provides the answer.