The Meta Pixel on its own captures only about 40% of the conversions on your site. Forty per cent. The remaining 60% — purchases, leads, add-to-carts — slip away thanks to ad blockers, iOS privacy settings and cookie restrictions.
Put another way: if you only have the Pixel and no CAPI, Meta optimises your campaigns on incomplete data. It's like driving a car where only half the instruments work. You're moving, but you have no idea how much petrol you have.
CAPI (the Conversions API) is the solution. Server-side tracking that sends data straight from your server to Meta — no browser, no cookies, no ad blockers. After implementing CAPI you typically see +20–30% more conversion data, ROAS improves by 10–25% and CPA drops by 15–18%.
It's not a nice-to-have. In 2026 it's mandatory kit.
In this article:
- What the Meta Pixel and CAPI are (simply)
- Why you need both — the numbers speak
- How to set it up on Shoptet, Shopify and WooCommerce
- Which conversion events to set up
- Event Match Quality — the hidden score that affects performance
- Diagnostics and troubleshooting
- FAQ
The summary for those who don't have time to read the whole article
- The Pixel captures roughly 40% of conversions. CAPI adds another 20–30%. Without CAPI, Meta optimises on incomplete data — you pay more for worse results.
- After implementing CAPI: ROAS +10–25%, CPA −15–18%. Improving Event Match Quality from 8.6 to 9.3 brought one online store −18% CPA and +22% ROAS. This isn't theory — these are measurable impacts.
- On Shoptet, Shopify and WooCommerce you can set up CAPI in 15–30 minutes. There's a step-by-step guide in the article. You don't need a developer.
- Event Match Quality (EMQ) above 8.0 is the target. Below 6.0 = your data is so incomplete that Andromeda can't optimise effectively. Check it in Events Manager.
- 5 mandatory conversion events: PageView, ViewContent, AddToCart, InitiateCheckout, Purchase. And above all — send the order value. Without it, Advantage+ can't optimise for ROAS.
What the Meta Pixel and CAPI are (simply)
The Meta Pixel — tracking via the browser
The Meta Pixel is a piece of JavaScript you place on your website. When someone visits a page, adds to cart or buys, the Pixel sends the information to Meta via the visitor's browser.
The problem: The browser is a middleman you can't always trust.
- Ad blockers block the Pixel for ~15–25% of users
- iOS 14.5+ — ~75–85% of iOS users refuse tracking
- Cookie restrictions — ~30–40% of Czech users refuse cookies
- Brave, Firefox, Safari have their own privacy protection
The result: the Pixel sees only part of reality. And Meta optimises on what it sees.
CAPI — tracking via the server
The Conversions API (CAPI) sends data straight from your server to Meta. No browser, no cookies, no ad blockers.
When a customer buys, your server (Shoptet, Shopify, WooCommerce) sends the information straight to Meta: “User XY just bought a product for 1,500 CZK (≈ €60).” Meta receives it even if the customer has an ad blocker or refused cookies.
Why you need both
The Pixel and CAPI aren't alternatives — they're complements. The Pixel captures online interactions (pageview, click). CAPI captures conversions (purchase, lead). Together they cover the maximum amount of data.
Meta merges the two through a process called deduplication — if both the Pixel and CAPI send the same conversion, Meta counts it only once. Don't worry about duplicates.
Why you need both — the numbers speak
Scenario | Captured conversions | ROAS | CPA |
Pixel only | ~40% | Baseline | Baseline |
Pixel + CAPI | ~65–75% | +10–25% | −15–18% |
Pixel + CAPI + optimised EMQ | ~80–90% | +20–30% | −18–25% |
A concrete example: an online store with 1,000 purchases a month.
- Pixel only: Meta sees ~400 purchases. It optimises on those.
- Pixel + CAPI: Meta sees ~700 purchases. It optimises more accurately.
- The impact: Meta gets a better understanding of who your customers are and finds more people like them. ROAS goes up, CPA goes down.
Why it's crucial for Advantage+
Advantage+ campaigns (which we wrote about in the ASC article) are fully AI-driven. AI learns from data. The more data, the better it learns. Without CAPI you're feeding the AI incomplete information — like teaching a child to read but covering half the letters.
Andromeda needs to know: who bought, what they bought, for how much and where they came from. The Pixel captures that for 40% of people. CAPI captures it for 70%. The difference shows up in the quality of optimisation — and that shows up in the results.
How to set it up on Shoptet, Shopify and WooCommerce
Shoptet (the most popular CZ platform)
Pixel:
- In Meta Business Suite → Events Manager → Data Sources → click “Add” → Web → Meta Pixel
- Copy the Pixel ID (a number)
- In the Shoptet admin → Marketing → Meta Pixel → paste in the Pixel ID
- Shoptet automatically sets up the standard events (PageView, ViewContent, AddToCart, Purchase)
CAPI:
- In the Shoptet admin → Marketing → Meta Conversions API
- Generate an Access Token in Meta Business Suite (Events Manager → Settings → Generate Access Token)
- Paste the Access Token into Shoptet
- Shoptet automatically links the server-side events with the Pixel
- Verify in Events Manager → Test Events
Time: 15–20 minutes. No developer.
Shopify
Pixel + CAPI (together):
- In the Shopify admin → Settings → Customer Events → Connect → Meta
- Sign in with your Meta account
- Shopify automatically links both the Pixel and CAPI
- Verify in Events Manager → Overview → Server Events should light up green
Time: 10 minutes. Shopify has the easiest implementation.
WooCommerce
Pixel + CAPI:
- Install the Facebook for WooCommerce plugin (the official Meta plugin)
- Connect via Meta Business Suite → sign in
- The plugin automatically sets up both the Pixel and CAPI
- In the plugin settings, check that “Conversion API” is enabled
- Verify in Events Manager
Alternative: The PixelYourSite plugin — more advanced options, CAPI support, custom events.
Time: 15–25 minutes.
After setup — verification
- Meta Pixel Helper — a free Chrome extension. Install it, open your site → the icon should light up green with the number of captured events.
- Events Manager → Test Events — Meta shows, in real time, which events are coming in from the Pixel and CAPI.
- Events Manager → Overview — check that you can see both Browser Events (Pixel) and Server Events (CAPI).
💡 **TIP:** After setting up CAPI, wait 48–72 hours before you start evaluating. Server-side data propagates with a slight delay. If you don't see Server Events after 72 hours, check the Access Token and permissions.
Which conversion events to set up
The 5 mandatory events for an online store
Event | What it tracks | Why it matters |
PageView | A visit to any page | The basis — nothing works without it |
ViewContent | Viewing a product page | Retargeting audience “viewed a product” |
AddToCart | Adding to cart | Retargeting audience “cart abandoners” |
InitiateCheckout | Starting an order | Audience “almost bought” |
Purchase | A completed purchase | The most important — this is what you optimise on |
Why send the order value
With the Purchase event, always send the order value in CZK. Without it, Advantage+ can't optimise for ROAS (the Min ROAS bid strategy). And Meta can't tell whether the customer bought for 200 CZK (≈ €8) or 20,000 CZK (≈ €800).
Shoptet, Shopify and WooCommerce all send the value automatically (if the plugin is set up correctly). Verify in Events Manager → click the Purchase event → check that the “Value” column contains numbers.
For services / lead generation
Event | What it tracks |
PageView | A page visit |
Lead | Filling in a contact form |
CompleteRegistration | Completing a registration |
Contact | A click on a phone number/email |
Schedule | Booking an appointment |
Event Match Quality — the hidden score that affects performance
Event Match Quality (EMQ) is a 0–10 score that says how well Meta can match a conversion event to a specific user. You'll find it in Events Manager → Overview → next to each event.
Why it matters
The higher the EMQ, the more accurately Meta knows who bought. And the better it can find similar people.
A real example: an online store raised its EMQ from 8.6 to 9.3 by adjusting the parameters it sends via CAPI. The result: CPA −18%, ROAS +22%. A single technical change — no new creatives, no higher budget.
How to raise EMQ
You raise EMQ by sending more user identifiers. Meta assembles a “puzzle” from them — the more pieces, the more accurately it works out who it was.
Identifiers (ordered by importance):
- Email (hashed) — the strongest identifier
- Phone (hashed) — the second strongest
- First and last name
- City, postcode, country
- External ID (your internal customer ID)
- Click ID (fbc) — automatically from the URL parameter
- Browser ID (fbp) — automatically from the cookie
Target: EMQ above 8.0. Ideally above 9.0.
Shoptet and Shopify send most parameters automatically. If your EMQ is below 8.0, check that the email and phone are being sent correctly at purchase.
💡 **TIP:** Check your EMQ right now. Events Manager → Overview → look at the score for the Purchase event. Below 6.0 = an urgent problem. 6.0–8.0 = room for improvement. Above 8.0 = a good baseline. Above 9.0 = excellent.
Diagnostics and troubleshooting
Meta Pixel Helper — your best friend
A free Chrome extension. Install it from the Chrome Web Store (search for “Meta Pixel Helper”). The icon appears next to the address bar.
How to use it:
- Open your site → click the Pixel Helper icon
- Green ✓ = the Pixel works, events are being sent
- Amber ⚠ = the Pixel works, but with a warning (a missing parameter)
- Red ✗ = the Pixel doesn't work or wasn't found
Go through the whole purchase journey: homepage → product page → cart → checkout → order confirmation. At each step, check which events the Pixel Helper reports.
Common problems and fixes
Problem: The Pixel isn't sending Purchase events
→ Check that the Pixel is on the order confirmation page. On Shoptet: Marketing → Meta Pixel → verify “Purchase tracking.”
Problem: CAPI isn't sending Server Events
→ Check the Access Token in the platform settings. Tokens expire — generate a new one in Events Manager.
Problem: EMQ is below 6.0
→ The email or phone probably isn't being sent at purchase. Check whether your checkout form requires these details and passes them to CAPI.
Problem: Duplicate events (both the Pixel and CAPI send the same conversion)
→ This is fine — Meta deduplicates automatically based on the Event ID. If you see double conversions in your reports, check that your plugin sets the Event ID correctly.
Problem: The Pixel Helper shows errors on a third-party site
→ Ignore it. The Pixel Helper responds to all Pixels on a page, including other people's. Look only at events with your Pixel ID.
Attribution changes — March 2026
In March 2026 Meta changed the definition of click-through attribution: only genuine clicks on a link count — not clicks on “See more” text, not clicks on the profile, not clicks on comments. Only clicks that lead to your page.
What does that mean? Your reported click-through conversions may fall, because the definition has been tightened. But the real performance of your campaigns hasn't changed — only the measurement.
Don't panic if your conversions “fell” in March/April 2026. Compare with GA4 and your own data, not just with Meta reports.
Conclusion
The Meta Pixel and CAPI aren't a technical detail for geeks. They're the foundation of everything you do in Meta advertising. Without quality data, Andromeda can't optimise. Advantage+ can't work. Retargeting can't target. And you pay more for worse results.
Three things for this week:
- Check your EMQ — Events Manager → Overview → the Purchase event. Below 8.0 = fix it.
- Install the Pixel Helper — Chrome Web Store, 30 seconds. Go through the purchase journey on your site.
- Verify CAPI — Events Manager → do you see “Server Events” next to “Browser Events”? If not, set it up following the guide above.
The investment: 30 minutes of setup. The return: +10–25% ROAS, −15–18% CPA. No other optimisation will get you this much in 30 minutes.
Frequently asked questions about Facebook advertising
What is the Meta Pixel and what is it for?
The Meta Pixel is a piece of code (JavaScript) that you place on your website. It tracks what visitors do — browsing products, adding to cart, buying. It sends this information to Meta, which uses it to optimise campaigns and for retargeting. Without the Pixel, Meta doesn't know whether your ads are working.
What is CAPI (the Conversions API)?
CAPI is server-side tracking — it sends conversion data straight from your server to Meta, without the browser. Unlike the Pixel, it isn't blocked by ad blockers or iOS privacy settings. In 2026 CAPI is a mandatory complement to the Pixel — without it you lose 20–30% of conversion data.
How do I set up the Meta Pixel on Shoptet?
Admin → Marketing → Meta Pixel → paste in the Pixel ID (find it in Meta Business Suite → Events Manager). For CAPI: Marketing → Meta Conversions API → paste in the Access Token. The whole setup takes 15–20 minutes with no developer. Shoptet automatically sends the standard events (PageView, ViewContent, AddToCart, Purchase).
What is Event Match Quality and why does it matter?
EMQ is a 0–10 score that says how accurately Meta can match a conversion to a specific user. You'll find it in Events Manager → Overview. The target: above 8.0. Raising EMQ from 8.6 to 9.3 brought one online store −18% CPA and +22% ROAS. You raise it by sending more identifiers (email, phone, name) via CAPI.
How do I know whether the Pixel and CAPI are working correctly?
Three tools: 1) Meta Pixel Helper (Chrome extension) — shows green/amber/red on each page. 2) Events Manager → Test Events — a real-time view of incoming events. 3) Events Manager → Overview — you should see both Browser Events (Pixel) and Server Events (CAPI). If you only see Browser, CAPI isn't set up.
Meta title: Meta Pixel and CAPI 2026: step-by-step setup
Meta description: The Pixel captures 40% of conversions. CAPI adds another 20–30%. A guide for Shoptet, Shopify, WooCommerce. EMQ, troubleshooting, impact on ROAS.
