- Meta Ads
- profitability
- method
The Facebook pixel: what it is, what it does, and how to tell if it works
The Meta pixel is the small piece of code that tells Facebook what your visitors do. What it measures, why it matters, and how to check it reports properly.
Published on · Joh · 6 min read
When people talk about Facebook advertising, the word pixel comes up straight away. Many businesses have heard they should "install the pixel" without knowing what it is for, or whether theirs works.
The answer fits in a few lines. Its consequences for your budget are wider.
What it is
The Meta pixel is a small piece of code placed on your site. It does not display anything, your visitors never see it. Its job is to tell Meta what happens: a page viewed, a product added to the basket, a purchase, a form sent.
Each of those actions is called an event. A well-placed pixel sends the right events, at the right moments, with the useful information.
What it is for
Three things, all of which matter for your budget.
Measuring. Without it, Meta does not know what your ads set off. You see clicks, you do not see what happened next.
Optimising. It is the algorithm's fuel. By telling it who bought or left their details, you let it show your ads to people who resemble them. Without that information, it delivers blind.
Speaking again to those who know you. The pixel lets you build audiences of people who have already visited your site, to show them a suitable message.
Why it is more fragile than you think
The pixel relies on the visitor's browser. It is that browser that sends the information to Meta.
If the visitor refused cookies, uses an ad blocker, or browses with a tool that cuts certain tracking, the event never arrives. The sale happened, Meta did not see it.
What Meta sees is therefore almost never the whole of reality. It is why the pixel is often completed by sending from the server, set out in the article on the Conversions API.
How to tell whether yours works
It is the question nobody asks, and the one that matters most.
Look at what Meta receives. Meta's events management tool shows the events arriving and how often. A browser extension offered by Meta, called Meta Pixel Helper, tells you for its part whether the pixel fires on a given page.
Cross-check against reality. The pixel can light up without sending anything useful. The real test is to compare what Meta counts with what your accounts or your diary record. A large gap points to a tracking problem.
Check that the events match your goal. A site selling jobs does not track the same actions as an online shop. A pixel that only reports page views does not let you optimise for contacts.
The most common faults
A pixel installed twice. Events are then counted double, and the results look better than they are.
A pixel not linked to the right ad account. The information exists, but it does not come back to where the campaign needs it.
An installation never rechecked. A site update or a change of tool can cut the tracking with nothing to show for it.
Tracking that counts something other than what interests you. Page views, when you need contacts.
Should you install it yourself
Depending on your site, there are several ways to place it, from the simplest to the most controlled. The choice depends on your tool, your volume and who will maintain the tracking over time.
For a business starting out in advertising, the method matters less than the result: the right event has to come through, and you have to be able to check it.
Further reading: The Facebook Conversions API and The Facebook advertising glossary. And to know who owns your pixel: Business Manager.
Not sure your tracking works? . We look at what Meta receives and compare it with what you take in.