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Cookie reference · Meta Pixel

The _fbp cookie

The Meta Pixel's first-party browser ID, used to match website events to the same browser for ad measurement and delivery.

_fbp at a glance

Cookie name
_fbp
Vendor
Meta Pixel
Category
Advertising
Party
First-party
Lifetime (observed)
90 daysObserved median across TagPipes scans. The vendor does not document a lifetime, so this is not its configured value.
Set on
.<your-domain>
Value format
fb.<subdomain-index>.<creation-time-ms>.<random-number>
Name match
Exactly _fbp

What the _fbp cookie does

The Meta Pixel creates _fbp on the site where it runs. The ID is sent with Pixel events, and can also be passed as the fbp parameter to Meta's Conversions API, so Meta can match website and server events to the same browser for ad measurement and delivery.

Meta documents the value format: fb, then a subdomain index (0 for a top-level domain like com, 1 for example.com, 2 for www.example.com), then the creation time in milliseconds and a random number. Meta's developer documentation doesn't state a lifetime for _fbp. 90 days is the widely cited figure and matches the median TagPipes observed.

What TagPipes observed

10%

of sites scanned set it (4,256 of 41,162)

90 days

median observed lifetime

TagPipes scanned 41,162 public websites between August 11, 2026 and September 13, 2026, loading up to three pages per site in a real browser as a first-time visitor. _fbp was present on 4,256 of them.

It was set as a first-party cookie on 4,142 sites and as a third-party cookie on 124. A site can count in both. Where it was stored as a persistent cookie, the median lifetime we recorded was 90 days.

Often found alongside

Percentage of sites with _fbp where the other cookie was also present.

Technologies detected on the same sites

  • Meta Pixel on 99% of them (13% of all sites scanned)
  • Google Analytics on 86% of them (55% of all sites scanned)
  • Google Fonts on 79% of them (78% of all sites scanned)
  • Google Tag Manager on 56% of them (30% of all sites scanned)
  • DoubleClick on 46% of them (11% of all sites scanned)

Aggregate figures across all sites scanned. Websites of TagPipes customers are excluded, no individual site is named, and cookie values are never read or stored. Snapshot dated September 13, 2026.

How to check for _fbp on a website

  1. Open the site in Chrome, then open DevTools (F12, or Cmd+Option+I on a Mac).
  2. Go to the Application tab and expand Cookies in the left panel.
  3. Select each domain listed there and look for _fbp. The Expires column shows when it will be deleted.
  4. If it is not there, reload the page. Many cookies are only set after a tag has loaded, and some only after a visitor has made a consent choice.

Sources

Purpose and value format checked against the vendor documentation above on . The observed lifetime and the figures under What TagPipes observed are TagPipes scan data from September 13, 2026, not values documented by the vendor. Vendors change their cookies, and sites can configure their own names and lifetimes. Browse all cookies.

Know every cookie your own site sets

TagPipes Pulse identifies the cookies dropped on your site and flags unclassified or miscategorized ones. Shield builds your cookie declaration from a real scan rather than a questionnaire.

See Pulse See Shield

TagPipes monitors, configures and reports. It does not determine legal compliance and does not provide legal advice. Output is informational and reflects observed state at the time of observation. Rawsoft's expertise is technology, not law; please confirm any regulatory interpretation with your own counsel.