Google Ads keyword economics

Search volume and CPC are the two numbers that tell you what a topic is worth. Here is what they actually mean, and how AdAstra measures them without guessing.

~6 min read . Google Ads

Before you write a single sentence of content, two numbers decide whether the topic is worth your time: how many people search for it, and how much advertisers pay when someone clicks a paid result for it. Together they are called keyword economics. Get them wrong (or make them up) and every downstream decision, from headlines to briefs, is built on sand.

What search volume actually measures

Search volume is reported as average monthly searches: how many times, on average per month, people typed (or spoke) a given keyword into Google over a recent period. It comes straight from the Google Ads Keyword Planner, the same tool advertisers use to plan campaigns.

It is an average, not a live counter, so treat it as a range indicator rather than a precise fact. A keyword with a few dozen average monthly searches did not get that exact count last month and will not get it again next month; it tells you the keyword sits in the "dozens per month" band rather than the "thousands" or "single digits" band. That is still enough to separate a topic worth a dedicated article from one that is not.

CPC: the price of intent

Cost-per-click (CPC) is what an advertiser pays, on average, each time someone clicks their ad for that keyword. AdAstra reports it as an integer number of EUR cents, not a rounded euro figure, because keyword economics are won and lost on small differences.

CPC is a proxy for commercial intent. Advertisers only bid what a click is worth to them, so a high CPC means real businesses believe a visitor searching that phrase is likely to buy, book or sign up. A keyword with high volume but near-zero CPC is popular but rarely converts into money; a keyword with modest volume and a high CPC is a smaller audience that is worth considerably more per visitor.

From advertiser bid to publisher earnings

The CPC an advertiser pays is not the CPC you earn as a publisher. It is the upstream input. AdAstra applies a fixed publisher revenue share of 0.68 to the advertiser CPC (via applyPublisherShare) to estimate what a site running display or contextual ads would realistically earn per click on that same topic. The result is floored, never rounded up, so the estimate never overstates what you would actually earn.

This is why AdAstra always shows the advertiser bid alongside your publisher earnings rather than one blended number: the advertiser figure explains why a topic carries commercial demand at all, and the publisher figure is the honest estimate of what that demand is worth to your site.

How AdAstra gets the numbers

Getting from a topic to real numbers is a two-phase flow. In phase one, Gemini reads your topic and brainstorms a shortlist of candidate keyword strings, roughly five to ten of them, in the same language as the topic. At this stage Gemini produces only text: it does not estimate volume or CPC itself.

In phase two, that shortlist is handed to the Google Ads service, which measures every candidate against live Google Ads data and returns actual average monthly searches and CPC for each one, split into the advertiser and publisher figures described above. Splitting the work this way keeps language and creativity where Gemini is strong, and keeps the numbers where only a real ads platform can be authoritative.

Why AdAstra never guesses

There is deliberately no fallback that lets an AI model estimate search volume or CPC when the Google Ads API is unavailable. If the Ads API call fails, whether from missing credentials, an authentication problem, an unapproved developer token or a temporary outage, AdAstra surfaces a clear, specific error instead of silently substituting a guessed number.

This matters because a fabricated number that looks exactly like a real one is more dangerous than an error message: an error tells you to try again later, while a plausible-looking guess can quietly steer a whole content strategy in the wrong direction. Keyword data you cannot verify is not data you should build a briefing on.

Reading the data: money-gaps

Once you have real volume and CPC for a set of keywords, the most useful thing to look for is a money-gap: a keyword with a high CPC (strong commercial intent) that your existing content does not rank for, or barely mentions. These are the topics where a competitor is capturing value that your site is currently leaving on the table.

A useful reading habit is to sort candidate keywords by CPC rather than by volume alone. A high-volume, low-CPC keyword can pad a traffic report without moving revenue, while a modest-volume, high-CPC keyword can be worth writing a dedicated section for even if it never becomes your top traffic driver.

The short version

• Search volume (average monthly searches) tells you how many people are looking, as a range, not an exact count.
• CPC, in EUR cents, tells you how much advertisers believe a click on that topic is worth: a proxy for commercial intent.
• AdAstra shows both an advertiser CPC and a publisher CPC, the latter scaled by a fixed 0.68 revenue share and floored, never inflated.
• Numbers come from a two-phase flow: Gemini brainstorms candidate keywords, Google Ads measures them for real.
• If the Ads API fails, you get an error, never a fabricated number: no silent guessing, ever.
• The best topics to target are money-gaps: high CPC keywords your content does not currently cover.