CAPI Match Rate

What CAPI match rate means

When you send a conversion to Meta through the Conversions API, Meta tries to match that event to a specific person in its system. The match rate — which Meta reports as Event Match Quality (EMQ) in Events Manager — reflects how successfully it can do that, based on the customer-information parameters you include with each event. A higher match rate means Meta can attribute more of your purchases to the right people, which directly improves how well its delivery algorithm optimizes your campaigns.

This matters because every conversion Meta can't match is a conversion that effectively didn't happen as far as optimization and reporting are concerned. Low match quality starves the algorithm of the very signal it needs, which shows up as higher cost-per-acquisition even when your real-world sales are fine.

The match keys that drive it

Meta matches on the customer-information parameters in the event's user_data object. Per Meta's Customer Information Parameters documentation, the high-value identifiers (sent SHA-256 hashed, except the cookie/IP fields) include:

• em — email (the single strongest key for most ecom)
• ph — phone number (E.164 format before hashing)
• fn / ln — first and last name
• external_id — your own stable customer ID
• fbp — the Meta browser cookie (not hashed)
• fbc — the click identifier derived from fbclid (not hashed)
• client_ip_address and client_user_agent

The rule of thumb: send more keys, hashed correctly, on every event. Email plus phone plus external_id, combined with the browser fbp/fbc from the pixel, gives Meta several independent ways to find the person.

What a healthy match rate looks like

Meta scores EMQ on a 0–10 scale in Events Manager. As an illustrative reading of that scale: above roughly 7.5 is healthy, above ~8.5 is strong, and below ~6.0 is a warning sign that Meta cannot match most of your purchases. These are interpretive guardrails, not a published Meta benchmark — the number that matters is the trend on your own events after you add match keys.

Illustrative example

A store sends Purchase events server-side with only email. EMQ reads around 6. Adding phone (E.164, hashed), external_id, and passing through fbp and fbc from the browser lifts EMQ into the 8s, and the share of purchases Meta can attribute rises accordingly. Because Meta now "sees" more conversions, the delivery algorithm optimizes more accurately and cost-per-purchase tends to settle lower. The exact numbers are an illustrative scenario — the durable lesson is that match keys, not budget, were the lever.

How to improve CAPI match rate

1. Send email, phone, and external_id on every event — not just Purchase, but earlier events too.
2. Hash correctly. Normalize first (lowercase/trim email, E.164 phone) then SHA-256. A formatting error silently zeroes a key's value.
3. Pass through fbp and fbc from the browser into the server event so cookie and click identity travel with the server-side conversion.
4. Deduplicate pixel and CAPI events with a shared event_id so the same purchase isn't double-counted.
5. Capture identity early (e.g. at email capture) so even pre-checkout events carry a strong key.

We break the seven highest-impact fields down in depth in the 7 CAPI fields that change match rate, and compare browser-pixel vs server-side matching in server-side CAPI vs browser pixel.

Common mistakes

• Hashing un-normalized data. "John@Email.com " and "john@email.com" hash to different values; only the normalized one matches.
• Sending keys on Purchase only. Earlier funnel events benefit from match keys too, and they help the algorithm learn.
• Trusting your server's view of match rate. Your server only knows what it sent; the EMQ number in Events Manager — scored after Meta's matching pipeline — is the one that drives optimization.

How Admaxxer improves match rate

Admaxxer ships server-side conversion tracking included, not as a separate add-on — capturing first-party identity, hashing it correctly, passing through the browser fbp/fbc, and deduplicating against the pixel automatically. It then surfaces which match keys are present on each event and how match quality is trending, so improving CAPI match rate becomes a dashboard you can act on rather than a guessing game inside Events Manager.