How the rules work
You pick a conversion event (a standard event, a custom event or All URL traffic) and add rules on the URL or on parameters the event already sends, such as value or content_id. Meta treats several values inside one parameter as "or" and separate rules as "and." If you choose All URL traffic or a custom event, you also pick a standard event category so Meta knows what kind of action to optimize toward. Meta says custom conversions aren't available for app events. This entry covers website events; offline events have their own custom conversion setup.
Optimizing for a custom conversion
Once Meta has received the custom conversion enough times, you can select it as the performance goal in Ads Manager, so delivery chases that narrower action instead of every purchase or lead. Meta says fewer rules mean a larger audience and more conversions, which matters for the optimization event volume a new ad set needs. Two limits: custom conversions can't optimize dynamic product ads (they can still measure them), and since September 2, 2025 Meta has been restricting custom conversions that suggest prohibited information, such as health conditions or financial status. Flagged ones can't be used in new campaigns.
When the URL never loads the pixel
A URL rule only counts visits the Meta pixel records. Meta says All URL traffic is built from PageView events and that the page behind a URL-based custom conversion must carry the pixel base code with the PageView event. URL equals also needs an exact match: UTM parameters, http instead of https, or a trailing slash all stop the count, which is why Meta suggests URL contains. A direct file download, such as a link straight to a PDF, has no page for the pixel to run on, so we track a thank-you page or an event on the click instead.
Common questions
How many custom conversions can a Meta ad account have?
100. Meta says you can delete the ones you no longer need and create new ones. Meta also archives custom conversions automatically if they are inactive or it hasn't received them in two years.
Can I optimize a Meta campaign for a custom conversion?
Yes. Select it as the performance goal when you create the ad set in Ads Manager. Meta says it must have received the custom conversion enough times first, and custom conversions can't be used to optimize dynamic product ads.
Why is my URL-based custom conversion not recording?
Usually the page isn't firing the pixel's PageView event, or a URL equals rule doesn't match exactly. Meta says extra text such as UTM parameters or a trailing slash prevents a count, and recommends URL contains with the shortest part of the URL that identifies the page.
What is the difference between a custom conversion and a custom event?
A custom event is an event your site or server sends to Meta. A custom conversion is a rule in Events Manager that filters an existing standard event, custom event or All URL traffic by URL or parameters, with no extra code.
What happens if I delete a custom conversion an ad set is optimizing for?
Meta says the ad set keeps delivering but may start to perform poorly, because Meta no longer matches or updates the custom conversion. Change the ad set's optimization first, then delete it.