Home / Tracking parameter reference
What each parameter in a Meta Pixel request means, from the event name to Advanced Matching, and the mistakes that cost a purchase its value or count it twice.
The Meta Pixel reports to https://www.facebook.com/tr/. Most events travel as a GET with
everything in the query string: the standard parameters, the custom data as cd[…] and any Advanced
Matching data as ud[…]. The pixel library itself loads from connect.facebook.net.
Which pixel, which event, and the id that lets the Conversions API recognise it.
| Parameter | What it means |
|---|---|
idPixel ID | The Meta pixel this hit reports to. Check it against the pixel in Events Manager — a wrong id looks perfectly healthy here and reports nowhere useful. |
evEvent Name | Event name. Meta only optimises for its standard events (Purchase, AddToCart, Lead…); anything else is a custom event. |
eidEvent ID (CAPI dedup) | Event ID. The same id must be sent by your server through the Conversions API, otherwise the browser event and the server event are counted twice. |
tsTimestamp | Timestamp the pixel put on the event. |
Where the event happened.
| Parameter | What it means |
|---|---|
dlPage URL | The page URL the event happened on. |
rlReferrer | The referrer. |
What you passed as the third argument of fbq('track', …).
| Parameter | What it means |
|---|---|
cd[value]Value | Purchase or conversion value. |
cd[currency]Currency | Currency of that value. |
cd[content_ids]Content IDs | Product ids, which must match the ids in your catalogue for dynamic ads to work. |
cd[content_type]Content Type | Whether the ids above are products or product groups. |
cd[contents]Contents | Products with quantity and price, as a JSON array. |
cd[num_items]Item Count | How many items the event covers. |
cd[search_string]Search Query | The search query, sent with a Search event. |
cd[<name>] | Custom data Meta received with this event. |
What ties the event to a person and to the ad click.
| Parameter | What it means |
|---|---|
fbpBrowser ID (fbp) | The browser id from the _fbp cookie — Meta's own client identifier. |
fbcClick ID (fbc) | The click id from the _fbc cookie, built from fbclid. Without it a conversion cannot be tied to the ad click. |
ud[em]Email (Hashed) | Customer email for Advanced Matching. Meta expects a SHA-256 hash; plain text here is a policy problem. |
ud[ph]Phone (Hashed) | Customer phone for Advanced Matching, SHA-256 hashed. |
ud[<field>] | Advanced Matching data about the customer. Meta expects every field SHA-256 hashed. |
The checks the Tag Master extension runs on every Meta Pixel hit it captures. Each is something the platform drops, cuts or misreports without saying so in its own interface.
Worth a lookA purchase with no event ID
If the same event is also sent server-side, Meta counts it twice and optimises on inflated numbers.
Fix: Add the fourth argument: fbq('track', 'Purchase', {…}, {eventID: ORDER_ID}) and send the same id from the server.
Dropped or wrongA value with no currency
Meta drops the value rather than guessing, so the conversion reports no revenue.
Fix: Send currency next to value in the same fbq call.
Dropped or wrongAdvanced Matching data sent unhashed
Meta rejects unhashed personal data and treats sending it as a policy breach.
Fix: SHA-256 the value, lowercased and trimmed, before it reaches the pixel.
Dropped or wrongA currency that is not a three-letter code
Platforms cannot convert an unknown currency, so the value is dropped or read as the account default — silently changing what the sale was worth.
Fix: Send the three-letter code: TRY, EUR, USD. Not the symbol, not lowercase.
Dropped or wrongA value that is not a plain number
A value carrying a currency sign, a thousands separator or a comma decimal reads as zero on the platform side.
Fix: Send 1649.25 — no symbols, no spaces, dot as the decimal separator.
Have a request in front of you? Paste it into the tracking request decoder and every parameter above is named on the hit itself, with these checks run on it. The Tag Master extension does the same for every request on the page, live.
The event ID. When the same event is also sent from your server through the Conversions API with the same ID, Meta keeps one and drops the other. Without it, the purchase is counted twice.
No. Meta expects Advanced Matching fields SHA-256 hashed — 64 hexadecimal characters. A readable email address in the request is sent in the clear and treated as a policy problem.
fbp is Meta’s browser ID from the _fbp cookie. fbc is the click ID from the _fbc cookie, built from the fbclid on the ad click. Without fbc a conversion cannot be tied to the click.
Other references: GA4 · Google Ads conversion · TikTok Pixel
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