Definition
What is the consent gap?
The consent gap is the difference between the conversions a company actually produces and the ones its advertising platforms can observe, once you remove the visitors who refused cookies. It does not close by switching tools. It is measured by comparing the sales recorded in the management system with the conversions the platforms report, it is stated in every report, and it is offset by tying real sales to the management system.
Why Consent Mode does not always close it
Google Consent Mode is not a banner. It is a mechanism that passes your visitors' choice to Google and adjusts tag behaviour accordingly. In the basic version, when the visitor refuses, no data is sent, not even the consent state; modelling then relies on a general model. In the advanced version, the tags send cookieless signals, which lets Google model from your real situation.
That modelling has a threshold, which Google's documentation sets at 700 ad clicks in seven days per domain country. Below it, the diagnostic tool shows that Consent Mode is implemented but that the required thresholds are not met: you recover nothing. A Quebec company spending a few thousand dollars a month at $3 or $4 a click does not get there, except at peak.
The three numbers to measure it
You cannot recover the refused data. You can know how much of it is missing, and that changes how you read your reports. Three numbers are enough, and you can pull them in half a day.
- The acceptance rate of your banner, which your consent management platform provides.
- The number of real sales recorded in your management system over the period.
- The number of conversions reported by your advertising platforms over the same period.
The gap between the last two numbers, set against the first, is your consent gap. If it is consistent with your refusal rate, the situation is understood. If it is much wider, you have another tracking problem, independent of consent, and it is better to know that before blaming the regulation.
What stays readable with partial measurement
Partial measurement stays usable, provided it is stable and reported. Comparisons over time stay reliable at a constant consent rate: if your measured conversions rise 30% from one month to the next while the acceptance rate has not moved, the increase is real, even if the absolute level is understated.
Two readings become false: comparisons between channels whose consent rates differ, and any return calculation in absolute value. A ROAS computed on 60% of the sales understates profitability and can get a campaign that pays cut. What stays true in every case is the sales in your management system: the only source that depends on no consent.
The three costly mistakes
- Trying to get around the refusal. Techniques that restore tracking despite a refusal expose the company to an administrative monetary penalty, up to $10 million or 2% of worldwide turnover, and settle nothing in the long run.
- Making the banner confusing to inflate acceptance. Consent obtained through an ambiguous flow can be found invalid: you keep the risk and data you have no right to use.
- Comparing periods before and after the banner. The drop in measured conversions when a banner goes live is not a drop in sales, yet it gets budgets cut every year.
What the law requires of your banner is a matter for legal advice; Falia is not a law firm. This entry is about measurement.
Consent gap = (recorded sales - reported conversions) ÷ recorded sales
Over the same period, with the sales from the management system on one side and the conversions from the advertising platforms on the other. The result is compared with your banner's refusal rate: a gap close to the refusal rate is understood, a much wider gap signals another tracking problem.
Take a fictional company that sells by quote. Over a quarter, its management system records 200 sales that came from the site. Google Ads reports 120. Its banner shows an acceptance rate of 60%, so a refusal rate of 40%. The consent gap is (200 - 120) ÷ 200, or 40%: it matches the refusal rate, and the situation is understood. Its diagnostic tool confirms that modelling is not active, since it does not reach 700 clicks in seven days.
Its monthly report now carries three lines: 120 reported conversions, an estimated gap of 40%, modelling inactive. A ROAS computed on the 120 conversions would understate the profitability of its campaigns by 40%.
We make the sales recorded in your management system the reference measure: it is the only source that depends on no consent and that will stay accurate whatever the regulatory or technical changes. The advertising platforms keep their role as optimization tools. They receive a signal, they train the bids, and their number serves to compare campaigns against each other, not to measure your revenue.
We report the gap in every report, in three lines: the acceptance rate for the period, the estimated gap between reported conversions and recorded sales, and the activation state of modelling. Before counting on modelling, we check the click volume and the diagnostic state. We refuse any workaround technique: a visitor who refuses stays refused, and that holds with server-side tagging too.
Not to be confused with
- Server-side tagging
- Server-side tagging changes the path of the measurement data, not the right to collect it. A visitor who refuses stays refused, wherever the tags run: it does not close the consent gap.
- Enhanced conversion
- An enhanced conversion ties a sale to a click that standard measurement would have lost, using information the person provided. It fills the gaps in consented measurement; it does not restore data the visitor refused to provide.
- Banner refusal rate
- The refusal rate is the share of visitors who say no to cookies. The consent gap is the share of sales the platforms no longer see. The two should look alike; when they diverge widely, the problem lies somewhere other than consent.
Related concepts
- Conversion
- Server-side tagging
- Enhanced conversion
- Administrative monetary penalty
- Cost per signed quote
- Executive dashboard
- ROAS
Further reading
- Consent and measurement: understanding Google Consent Mode's limits
- Quote-based sales: calculating your cost per sale
- Conversion tracking: connecting your campaigns to actual sales
- Server-side tagging: benefits, limitations and costs
- Quebec Law 25 and marketing: forms, cookies and email lists
- Marketing dashboard: 6 metrics for leadership teams
Related services
Frequently asked questions
My conversions dropped since the cookie banner, did I lose sales?
Almost never. Compare the same period in your management system: if sales are stable, you did not lose customers, you lost visibility into them. It is the most costly interpretation error in this file, because it gets working budgets cut.
Does Google Consent Mode recover my lost conversions?
Only if your account reaches the modelling threshold, which Google sets at 700 ad clicks in seven days per domain country. Below it, the feature is implemented but inactive. Check the state in the diagnostics tab of your conversion actions before counting on it.
What should I write in my monthly report?
Three lines: the acceptance rate for the period, the estimated gap between reported conversions and recorded sales, and the activation state of modelling. They keep a partial number from being read as a total, which is the starting point of most bad decisions on this subject.
