What Is Conversion API (CAPI)?
The Conversion API (CAPI) is a server to server stream of conversion events sent from your site or CRM directly to Meta or Google. It replaces or complements the browser Pixel, so events survive ad blockers, cookie limits, and iOS 14 tracking restrictions.
Also known as: capi, meta capi, conversions api, facebook capi, conversions api setup. This page answers "what is Conversion API", Conversion API formula,Conversion API calculation, and Conversion API benchmarks for Bangladesh and global performance marketing teams.
Why CAPI matters in practice
A Shopify store fires 1,000 purchase Pixel events in a week. After iOS 14, Meta only receives 620 of them on the browser side. Turning on CAPI sends the same purchase from Shopify's server to Meta, deduplicated by event ID. Meta now attributes closer to 950 of the 1,000, and the optimisation algorithm has a cleaner signal to train on. CPA usually falls 8 to 20 percent within 2 weeks of a clean CAPI setup.
Benchmarks
- Event Match Quality (EMQ) target: 7 or higher on all core events.
- Pixel plus CAPI recovery over Pixel-only: typically 20 to 40 percent more attributed events.
- Deduplication rate: aim for 90 percent plus so Meta does not double-count.
- Server events should include email, phone, external_id, IP, and user agent for match quality.
Meta's own CAPI documentation reports advertisers combining Pixel + CAPI see an 8-13% lower cost per action versus Pixel-only, driven by higher event match quality.
Why it matters
The ad platform can only optimise for what it can measure. If iOS blocks 30 percent of your Pixel events, the algorithm trains on a broken sample and delivers to a worse audience. CAPI is the single highest-ROI tracking upgrade in 2026 for accounts still relying on Pixel alone.
Common mistakes
- 1.Sending CAPI without deduplication IDs. Meta counts every purchase twice.
- 2.Skipping hashed customer data (email, phone). EMQ drops, matching gets worse than Pixel-only.
- 3.Running CAPI through GTM client container instead of server-side. You gain almost nothing.
- 4.Not testing in Events Manager before scaling. Broken payloads run silently for weeks.
Put Conversion API to work
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FAQs about Conversion API
Do I still need the Pixel if I have CAPI?
Yes. Meta recommends running both and deduplicating by event_id. Pixel adds browser context that server events lack, and CAPI adds coverage the browser loses. Together they beat either one alone.
How long does CAPI take to set up?
Shopify or Woo with a native integration, 30 minutes. Custom stack with server-side GTM, 1 to 3 days including QA. Anyone quoting a week for the code alone is padding.
Will CAPI double-count my conversions?
Only if you skip deduplication. Meta uses event_id plus event_name plus timestamp to match Pixel and CAPI events to the same conversion. Get that right and the counts stay clean.
Go deeper
Long-form reads that show Conversion API applied end to end.
Related terms
Browser tag that reports events (view, add-to-cart, purchase) to Meta.
Meta's 0 to 10 score of how well events match to a Meta user.
Running Tag Manager on your own server to improve match + control.
Google's hashed first-party data sent server-side to recover lost matches.
Google's consent signalling API; required in EEA for ad measurement.
URL tags that pass source/medium/campaign into your analytics.
Feeding CRM/sales data back to ad platforms to optimise on real outcomes.
Meta audience built from your customer, pixel, or engagement data.