There's a decent chance Google can't see a third of your sales right now. Maybe more. And when Google's Smart Bidding algorithm is working from a dataset with that many transactions missing, it makes poor decisions — underbidding on your best customers, losing auctions it should win, misjudging which campaigns are actually driving revenue.

I've been dealing with this problem across multiple client accounts over the past year. The pattern is always the same: the revenue figures in Google Ads don't match the revenue in the back end. The gap varies — I've seen it anywhere from 20% to over 70% — but the cause is almost always the same thing. The tracking code connecting your ad clicks to your sales is being blocked before it can do its job.

The solution I've been implementing is a two-step setup using Cloudflare and a feature built directly into Google Ads called the Google Tag Gateway. I've now rolled this out across several clients, and the improvements in attribution — and as a result, in Smart Bidding performance — have been significant enough that I think it's worth explaining in full.

Why Your Conversion Tracking Is Probably Broken

When someone clicks your Google Ad and lands on your website, standard conversion tracking works by running Google's JavaScript tag — gtag.js — in the visitor's browser. When a purchase is completed, that script fires a conversion signal back to Google.

The problem is that the entire chain runs inside the visitor's browser. And browsers have been quietly making that chain less and less reliable for years:

  • Ad blockers — uBlock Origin, Privacy Badger, and similar tools actively block Google's tracking script. In some audiences, particularly among developers, designers, and technically-minded shoppers, adoption is well over 30%.
  • Apple's Intelligent Tracking Prevention (ITP) — Safari, which runs on every iPhone and iPad, limits the lifetime of cookies set by JavaScript to as little as 24 hours. Someone who clicks your ad on Monday and buys on Wednesday? That attribution is gone.
  • Browser privacy modes — Firefox's Enhanced Tracking Protection and Chrome's own privacy settings both intercept tracking requests in certain configurations.
  • Corporate firewalls — Relevant for B2B businesses. IT departments commonly block third-party tracking scripts as policy.

The result: a meaningful proportion of your customers are making purchases that Google simply cannot see. Smart Bidding — which decides how much to bid for every single auction — thinks your campaigns are less effective than they are. So it bids less. You lose auctions you should be winning.

One client I work with had a conversion attribution rate of just 28% before we addressed this. That means for every 100 orders that came through their site, Google could see fewer than 30 of them. The bidding algorithm was making every decision based on less than a third of the actual picture.

The Fix: Cloudflare + Google Tag Gateway

The root of the problem is that Google's tracking tags make requests directly to Google's own servers — googleadservices.com, google-analytics.com — and those third-party requests are exactly what privacy tools target. Ad blockers recognise them and block them. Safari's ITP treats the cookies they set as third-party, cutting their lifetime down to almost nothing.

The fix is to route those requests through your own domain instead. When a conversion signal goes to yoursite.com/_gtag/ rather than directly to googleadservices.com, browsers and ad blockers treat it as a first-party request — your site talking to itself. They leave it alone. Cookies set in this context get the full 13-month lifetime that browsers allow for first-party data, rather than the 24-hour cap imposed on third-party cookies.

This is exactly what the Google Tag Gateway does. And the setup — once your domain is running through Cloudflare — is built directly into Google Ads. No code changes on your website. No developer needed for the tracking side. Just a connection between Google Ads and your Cloudflare account, and Google handles the rest.

The implementation is two steps:

Step 1 — Put your domain on Cloudflare. Move your domain's DNS to Cloudflare by changing your name servers at your registrar. All traffic to your site then flows through Cloudflare's network. This is the prerequisite that makes everything else possible.

Step 2 — Activate Google Tag Gateway. In Google Ads, navigate to Tools → Data Manager → Google tag → Admin → Google tag gateway. Sign in with your Cloudflare credentials. Google and Cloudflare configure the first-party routing automatically. Your conversion tracking starts working better immediately.

That's it. What happens behind the scenes is that Cloudflare deploys configuration on your domain so that Google's tag requests are proxied through your own domain path before being forwarded to Google's servers. Your existing conversion tags, conversion actions, and campaign structure remain entirely unchanged. Only the routing changes.

What Changes — Before and After

Before the Gateway, a conversion event travels like this: customer purchases → Google tag fires → request goes to googleadservices.com → ad blocker sees a third-party request and blocks it → conversion never reaches Google Ads.

After: customer purchases → Google tag fires → request goes to yoursite.com/_gtag/ → Cloudflare proxies to Google → conversion attributed correctly.

The conversion signal takes an additional hop through Cloudflare, but it arrives at Google with far greater reliability. And because the request now originates from your own domain, cookies persist for 13 months rather than 24 hours. That's transformative for longer purchase cycles: a visitor who clicks your ad on a Monday and buys three weeks later will still be attributed correctly.

Real Results From Two Implementations

A large online furniture and accessories retailer (PrestaShop)

Before the Cloudflare implementation, this business had an attribution rate of 28%. Nearly three-quarters of their Google Ads-driven orders were invisible to the algorithm. Smart Bidding was, in effect, learning from a highly unrepresentative sample.

After going live, attribution jumped to over 50% — exceeding their 40% target — and the volume of conversion signals flowing into Smart Bidding increased by 70%. Google Ads automatically created a new, higher-quality conversion path within 24 hours of the implementation, which only happens when Google detects a sustained and significant improvement in the click data it's receiving. All of that happened without a single change to their website code or campaign structure.

A B2B lighting supplier (Shopify)

This client sells primarily to trade buyers — interior designers, contractors, project managers. The typical journey spans multiple sessions across multiple devices over multiple days. Exactly the scenario where 24-hour cookie windows cause the most damage.

The 13-month cookie lifetime delivered by Google Tag Gateway was particularly valuable here. A buyer researching products over a week and then placing an order is no longer a lost attribution. The conversion signal travels through the first-party domain path regardless of how much time has elapsed since the original click.

Their overall tracking rate improved from 64.7% to 78% — a 13+ percentage point gain. Not a dramatic number in isolation, but fed into Smart Bidding on a monthly six-figure ad spend, the compounding effect on bid quality is significant.

One important note on both implementations: when you significantly improve your conversion signal, Smart Bidding responds, and sometimes quickly and aggressively. I saw spend increase in the weeks after going live on both accounts as the algorithm recalibrated to the richer data. This is the system working correctly, but it means you need to monitor spend closely during the first two to four weeks and be ready to tighten your target ROAS or daily budgets if needed.

How to Set It Up

The Cloudflare migration

If you're not already on Cloudflare, the setup involves migrating your domain's DNS by changing name servers at your domain registrar. Cloudflare automatically imports all your existing DNS records, and you review them before making the switch.

A few critical points:

  • Website records (your A record and www CNAME) should be set to proxied — the orange cloud icon in Cloudflare's DNS panel. This is what routes traffic through Cloudflare's network.
  • Mail records (MX records) must be set to DNS only — grey cloud. If MX records are proxied, email breaks. This is the most common error.
  • Do the migration overnight. If there's a DNS misconfiguration, your site may briefly be unreachable. Quiet hours means less impact and you can roll back quickly.
  • DNS propagation typically completes within an hour or two, though it can technically take up to 48 hours.

Activating Google Tag Gateway

Once Cloudflare shows your domain as Active, go to Google Ads and navigate to:

Tools → Data Manager → Google tag → Admin → Google tag gateway

Click "Sign into Cloudflare", authenticate with your Cloudflare credentials, and select your domain. Click "Complete setup". Google and Cloudflare handle the configuration automatically — deploying the routing infrastructure, setting up the measurement paths, updating cookie contexts. You should see Active status within a few minutes.

To verify it's working: open your browser's developer tools, go to the Network tab, and load your site. You should see conversion-related requests going to your own domain path (something like yoursite.com/_gtag/) rather than directly to google-analytics.com or googleadservices.com.

How Easy Is It on Different Platforms?

The Cloudflare migration and Google Tag Gateway activation are the same regardless of your e-commerce platform. The key question is whether your checkout lives on the same domain as your main site — in which case Cloudflare covers it automatically — or on a separate subdomain.

  • Shopify — Straightforward. The main domain and checkout subdomain need Cloudflare proxying. Shopify's native Google & YouTube sales channel provides the Google tag; GTG automatically upgrades it to first-party routing. No changes to the Shopify setup itself.
  • WooCommerce — Straightforward. Everything runs on your own domain. Cloudflare covers it all automatically. GTG works particularly cleanly on WooCommerce sites.
  • PrestaShop — Straightforward. Self-hosted, single domain, identical to WooCommerce.
  • Magento / Adobe Commerce — Straightforward for single-store installations. Multi-store setups with separate subdomains per region need Cloudflare proxying confirmed on each and GTG activated per domain.
  • BigCommerce — Straightforward. Standard setup, no platform-specific complexity.
  • Bespoke — No code changes needed on the website. The Cloudflare migration and GTG setup are infrastructure changes only.

On cost: Cloudflare's free plan is sufficient for Google Tag Gateway — the feature is available at every pricing tier. The Pro plan (around £20 per month) adds CDN performance, advanced security, and analytics. Worth having either way, but the tracking improvement itself doesn't require it.

Who Benefits Most

Google Tag Gateway improves conversion measurement for any business running Google Ads, but the gains are largest in specific situations:

  • B2B e-commerce — Long purchase cycles, multi-device journeys, corporate browsers with strict privacy policies. The shift from 24-hour cookies to 13-month cookies is transformative when buyers take days or weeks to complete a purchase.
  • Technical or design-savvy audiences — Developers, designers, architects, IT professionals. Ad blocker rates in these groups are high. If your customer base skews technical, a significant proportion of them are blocking your tracking by default.
  • High average order value products — The more research-intensive the purchase decision, the more sessions a buyer takes before converting. Standard cookie windows struggle here.
  • Any business using Smart Bidding — Target ROAS, Target CPA, Maximise Conversion Value. All of these learn from your conversion data. Better data means better bids. Better bids means winning the right auctions at the right price.

The Bigger Picture

The direction of travel on browser privacy is well established and it's not reversing. Safari's ITP tightens with each major iOS release. Firefox's tracking protection keeps improving. Chrome's own privacy tools extend further with each release. Client-side conversion tracking was always structurally vulnerable — it relied on browsers cooperating with third-party measurement. That cooperation is being withdrawn, steadily and systematically.

What makes the Google Tag Gateway approach compelling is that it works within Google's own infrastructure. It's not a workaround or a hack — it's a feature Google built and actively promotes, precisely because better data is in everyone's interest. It upgrades your existing tracking to first-party status without requiring any changes to what you've already built.

At roughly £20 per month for Cloudflare and zero ongoing cost for the Gateway itself, the barrier is low. The gains in attribution — and in the Smart Bidding decisions that flow from attribution — have been material in every implementation I've done.

If your Google Ads conversion numbers don't match your platform's order numbers, this is almost certainly a significant part of the reason. And the fix, as these things go, is remarkably straightforward.

I'm Peter Empson. I've been running Google Ads campaigns for e-commerce businesses for over 25 years, and tracking setup is one of the first things I look at with any new account — because bad data is usually the root cause of campaigns that look fine but underperform. If you'd like me to take a look at your conversion tracking and tell you honestly what it's missing, get in touch — no obligation, no sales pitch.