You spend on ads every day, and Ads Manager reports dozens of "conversions". Yet in the evening, the delivered parcels do not match. This gap almost always comes from a poorly configured Facebook and TikTok pixel. The good news: it can be fixed.
In this article, we look at what a pixel really measures, why it loses information and how to connect it to your real sales, including with cash on delivery.
What a pixel actually does
A pixel is a small script placed on your site. It tells the ad platform what the visitor does: views a product, adds it to the cart, places an order. Then the algorithm uses these signals to show your ads to people who resemble your buyers.
In other words, the pixel does not just count. It trains the algorithm. So wrong or missing signals produce badly targeted ads.
The events to track first
- ViewContent: the visitor views a product page.
- AddToCart: they add a product to the cart.
- InitiateCheckout: they start the order.
- Purchase or Lead: the order or request is sent.
For example, if you sell through an enquiry form rather than a cart, the Lead event is more accurate than Purchase.
Why the browser pixel is no longer enough
The classic pixel runs in the browser. However, many visitors use ad blockers, and browsers restrict tracking more and more. As a result, some events never reach Facebook or TikTok.
That is why both platforms offer server-side sending: the Conversions API at Meta and the Events API at TikTok. Your site sends the event itself, directly from the server, without relying on the browser.
Setting up your Facebook and TikTok pixel properly
- Install the browser pixel on every page.
- Turn on server-side sending with the token each platform provides.
- Use the same event ID on both sides, so the platform merges duplicates (deduplication).
- Test with the test event code before launching your campaigns.
That way, you recover lost events without counting the same order twice.
The cash-on-delivery case
With cash on delivery, a placed order is not yet a sale. Some will be cancelled, others refused at the door. So you need to separate placed orders from confirmed orders, then compare with actual deliveries.
In practice, calculate your cost per delivered order, not per placed order. This is often where you discover that a "profitable" campaign is not. To narrow the gap, apply the advice in our article on reducing returns.
The most common tracking mistakes
- The pixel installed twice, by the theme and by a plugin: every order counts double.
- The Purchase event firing on every reload of the thank-you page.
- No value or currency sent: the algorithm cannot tell a small basket from a big one.
- One pixel shared by several stores: data gets mixed and optimisation becomes blurry.
In short, before increasing a budget, always check that your numbers are clean. One hour of checking can save weeks of misdirected spending. It also helps to compare Ads Manager figures with the parcels actually delivered every week.
Respecting your visitors' privacy
Finally, tracking must stay transparent. A cookie banner lets you load pixels only after the visitor agrees. Likewise, a clear privacy policy explains which data is used and why.
What our platform does
Our sites include the Facebook and TikTok pixel on both the browser and server side, with automatic deduplication, plus Google Analytics, Google Ads and other tags. Pixels can even be added page by page, for example on a campaign landing page. See our e-commerce service or ask for an audit of your tracking. For Meta's official documentation, see the Conversions API page.