Event Match Quality (EMQ) is a score from 0 to 10 that Meta gives each conversion event, showing how well the customer details sent with that event let Meta link it to a real Facebook or Instagram account. A high score means Meta can usually tell who bought or enquired; a low score means many of your conversions arrive as anonymous signals the ad system cannot learn from.
How Event Match Quality works
When your website reports a purchase or lead, it can attach customer information parameters: email address, phone number, first and last name, town, postcode, country, an external ID from your own system, the visitor’s IP address and browser user agent, and the click and browser IDs that Meta stores in first-party cookies. Personal fields such as email and phone are normalised and scrambled with hashing before they leave your server, so Meta compares hashed values rather than reading the raw details.
Meta looks at which parameters arrive, how often they are present and how reliable each one is for matching, then turns that into the score you see per event in Events Manager, alongside a label such as Poor, OK, Good or Great. The score is mainly reported for events sent from your server through the Conversions API, because a server can usually send more of these fields than a browser pixel can. Email and phone carry the most weight; IP address and user agent on their own match far fewer people.
Why it matters for a UK business
Every unmatched conversion is a sale or enquiry Meta cannot credit to an ad or use to find similar buyers. With iPhone tracking prompts, cookie banners and ad blockers all removing browser data, the events that do reach Meta need to carry as much matching information as you are allowed to send. Better matching usually means more conversions reported, steadier delivery in campaigns optimised for purchases or leads, and better raw material for custom audiences.
The UK rules sit on top of this. Under UK GDPR and PECR you need a lawful basis and, for most tracking, the visitor’s consent, and your privacy notice should say that you share hashed contact details with Meta for advertising. Chasing a higher score by sending data from people who declined cookies is a compliance problem the ICO takes seriously, not a clever workaround.
Common mistakes
- Sending only IP address and user agent from the server, then wondering why the score sits at 3 or 4.
- Collecting an email at checkout but not passing it with the purchase event.
- Formatting phone numbers inconsistently, for example sending 07700 900123 without the 44 country code, so the hash never matches.
- Dropping the click ID cookie when the server event is built, which loses the strongest link back to the ad.
- Treating the score as the goal. A 9.0 on an event you do not optimise for is worth less than a 7.0 on your purchase event.
How to act on it
Open Events Manager, choose your dataset and look at the score for each event you optimise campaigns towards, usually Purchase or Lead. The detail view lists which parameters are being received and what share of events carry each one, which tells you where the gaps are.
Then work through the gaps in order of weight. Pass hashed email and phone (in international format, with the 44 prefix) wherever the visitor has given them, add an external ID such as your customer number, and make sure the click and browser IDs travel from the page to the server event. If you also run the pixel, switch on advanced matching and use the same event ID in browser and server events so Meta removes duplicates. Retest in the Test Events tool after each change. When I take on Facebook and Instagram ads management, the tracking and match quality check comes before any budget decision.