Why your Google Ads leads cost more every quarter

Every account I take over arrives with the same sentence attached: "it used to work." Leads used to cost forty pounds. Now they cost ninety. Nothing obvious changed, so the assumption is that Google got greedy.

Sometimes it did. Mostly it did not. Here is the arithmetic that settles it.

Separate the two numbers that make up cost per lead

Cost per lead is only ever two things multiplied together:

Cost per lead = cost per click ÷ conversion rate

So when CPL doubles, exactly one of those moved, and it is trivial to find out which. Pull a twelve-month view in Google Ads with CPC and conversion rate side by side.

In four out of five audits I run, it is row two or row three. The auction is a convenient thing to blame because nobody can argue with it.

Cause one: broad match quietly ate your budget

Broad match with smart bidding is genuinely good now, but it drifts. It starts on your core terms and gradually spends more on the adjacent ones, because those are cheaper and technically still convert — just worse.

Open the search terms report, set it to the last 90 days, sort by cost descending, and read the top fifty terms. Not the top five. The fifty. You are looking for the queries that are related to your service rather than requests for it.

Worth knowing: a term converting at 2% when your account average is 9% is not a bad keyword you should bid lower on. It is a different intent, and it belongs in a negative list.

Cause two: the landing page stopped matching the ad

This is the one that costs the most and gets checked the least. Ads get rewritten. Offers change. The landing page does not, because changing it means talking to whoever built it.

The result is a slow divergence: the ad promises a free consultation, the page leads with a service description and buries the form. Every click still costs the same. Fewer of them convert.

On a dental account I took over, the ads were fine. The page was a treatment brochure with a contact form at the bottom. Rebuilding it around a single action — book a consultation — alongside a tracking fix took cost per lead down 69% on the same monthly budget, and return on ad spend to 7.5× within sixty days.

Cause three: your tracking is over-reporting

If your conversion action fires on a page view rather than a genuine submit, or you are counting the same lead twice through two tags, your reported CPL is fiction — and Smart Bidding is optimising towards that fiction.

This gets worse over time, which is why it feels like decay. The algorithm keeps finding more of whatever triggers the false conversion.

Check it in ten minutes: submit your own form, then look at whether the conversion count went up by exactly one. If it went up by two, or went up when you merely loaded the thank-you page directly, you have found your problem.

Cause four: you never changed the creative

Search is more forgiving than social here, but it is not immune. Ad fatigue on Search shows up as a slow CTR decline, which lifts your cost per click through Ad Rank rather than through the auction itself.

If your responsive search ads have not been touched in a year, your competitors have written newer copy against them, and the auction is comparing the two.

What to actually do this week

1. Pull the twelve-month CPC-versus-CVR view. Ten minutes, and it tells you which of the four causes you have.
2. Read the top fifty search terms by cost. Negative out anything that is adjacent rather than intent.
3. Submit your own form and verify the conversion count moves by exactly one.
4. Load your landing page as a stranger would and ask what it wants you to do. If you cannot answer in three seconds, neither can the click you paid for.

None of this requires more budget. That is rather the point: an account leaking on conversion rate does not get better when you feed it more money, it just gets more expensive at a larger scale.