Free tools · Measurement

Consent Mode Conversion Loss Estimator

Cookie banners hide conversions from Google Ads, and accounts that bid to reported numbers quietly underbid. Estimate what you're not seeing, your real CPA, and the bid target adjustment that fixes it. Everything runs in your browser.

1 · Your numbers
Results update live. Nothing is uploaded; the maths runs in your browser.
100%
UK-only business? Leave at 100%.
75%
From your CMP dashboard. UK banners typically see 60 to 90%.
70%
Google cites ~70% average recovery with proper consent mode setup.
CONVERSIONS GOOGLE CAN'T SEE
~10/mo
7.5% of the real total
ESTIMATED REAL CONVERSIONS
~130/mo
vs 120 reported
REPORTED CPA
£40.00
ESTIMATED REAL CPA
£37.00
2 · What this means for your bid targets
Your account performs about 8.1% better than Google Ads reports. If a conversion is truly worth a CPA of £X to you, Smart Bidding can be allowed an observed target of £X × 1.08, because for every conversion it reports, roughly 1.08 really happen. Work out your true break-even £X with our break-even calculator, then apply the factor. Underbidding against invisible conversions is how consent-compliant accounts quietly strangle their own delivery.

The measurement gap UK advertisers keep paying for

Since consent mode became mandatory for UK and EEA traffic, every Google Ads account has two performance realities: the one in the interface and the one in the bank. When a quarter of visitors decline tracking, a chunk of real revenue simply never appears against the campaign that drove it. The damage isn't just cosmetic reporting: Smart Bidding optimises to observed conversions, and break-even targets computed from under-counted data make the algorithm bid as if the account performs worse than it does. The result is a slow strangulation: less aggressive auction entries, lost volume, and a "CPA got worse" narrative that's actually a measurement artefact. The fix costs nothing: estimate the visibility gap honestly and let your targets breathe by that factor.

How to use this tool

  1. Enter a month of reported conversions and spend from Google Ads.
  2. Set the share of your traffic under UK/EEA consent rules (a UK-only business is 100%) and your consent accept rate from your CMP.
  3. Toggle conversion modelling on if you run consent mode v2, and adjust the recovery assumption to taste.
  4. Read the gap, then pair the adjustment factor with our break-even calculator to set targets from true economics.

FAQ

Why does Google Ads under-report my conversions?
Users in the UK and EEA who decline cookie consent can't be tracked from click to conversion. They still convert; Google just can't attribute it. Consent mode's conversion modelling recovers a share statistically, but rarely all of it.
Where do I find my consent accept rate?
In your consent management platform's dashboard (Cookiebot, OneTrust, CookieYes and similar all report it). UK sites typically see somewhere between 60 and 90% depending on banner design.
Is the 70% modelled recovery figure reliable?
It's Google's cited average for advertisers with consent mode properly implemented, and real recovery varies by vertical and volume. That's why it's an adjustable slider: set it to 0 if you don't run consent mode, or lower it if you're sceptical.
Should I actually raise my tCPA?
Directionally yes, if your targets were set from break-even economics on reported numbers, you're underbidding. Apply the factor gradually (10 to 15% steps) and watch delivery and downstream revenue, not just the reported CPA.
Not sure your consent mode is even wired up correctly? Broken implementations lose far more than banners do. Our free audit checks it.