fbclid

The fbclid (Facebook Click Identifier) is an ID that Meta appends to links when someone clicks through to your website from Facebook or Instagram – for example ?fbclid=IwAR2…. It allows a later conversion to be tied precisely to that click and therefore to the ad.

How the fbclid works

1. A user clicks your ad on Facebook or Instagram.
2. Meta appends the fbclid to the landing page URL.
3. The Meta Pixel reads the fbclid and stores it in the first-party cookie _fbc (format fb.1.timestamp.fbclid).
4. When a conversion happens, this fbc value is sent along – by the pixel in the browser or via the Conversion API.

Like the gclid on Google, the fbclid isn't human-readable and only Meta can make sense of it.

Example

An online coach promotes a webinar on Instagram. An attendee signs up and three weeks later buys a $2,400 coaching program through Digistore24. If the fbclid was stored at sign-up, the purchase can be sent to Meta as a conversion with the fbc value. Meta knows exactly which ad generated the revenue – even if the pixel was blocked on the checkout page.

fbclid for lead generation

With long decision cycles, the deal no longer happens in the browser. For Meta to still attribute it to the right ad, the fbclid has to be stored with the lead and sent later from the server. The more matching data (click ID, hashed email, phone number) an event contains, the higher its Event Match Quality.

LeadMetrics stores click IDs like the fbclid in the session, links them to the lead and sends leads, purchases and deals with fbc and fbp to Meta via the Conversion API. For more background, read about the Meta Andromeda update.

Common mistakes

• Losing the fbclid: Redirects or form tools on other domains strip the parameter.
• Cache and SEO issues: Every fbclid creates a new URL variant. A canonical tag prevents duplicate content.
• Relying on the pixel alone: If the pixel is blocked, the _fbc cookie isn't set either.