If you’ve ever compared your Meta Ads Manager and FERMÀT funnel analytics and thought, “Why don’t these numbers match up?”, you’re not alone.
This guide explains why Meta typically reports more conversions than FERMÀT. The differences stem from three key factors: varying attribution windows, different conversion definitions, and what's known as the Halo Effect.
We’ll walk through:
What is Attribution?
Attribution in digital marketing refers to the process of identifying which marketing efforts lead to conversions or desired customer actions. Different platforms use different methods to determine when a purchase should be "credited" to a specific marketing channel.
FERMÀT’s Attribution Model
FERMÀT uses same-session attribution. This means it only counts conversions when a shopper clicks on your ad and makes a purchase within the same browsing session.
It’s a clean and conservative method that tells you exactly how many purchases came from people who saw the ad and immediately converted.
This approach is great for understanding:
How effective your funnel is at driving instant conversions
What’s happening in real time on your FERMÀT experiences
Meta Ads Manager’s Attribution Model
Meta takes a broader approach. By default, it uses a 7-day click and 1-day view attribution window.
This model is designed to show the longer-term impact of your ad campaigns, not just the instant conversions.
Meta's attribution model means:
If someone clicks your ad on Monday and buys on Friday, Meta counts it.
If someone sees your ad (but doesn’t click), then Googles your brand and buys the next day, Meta still claims credit.
If someone clicks your ad on mobile, then completes their purchase later on desktop — it’s still included in Meta’s report.
Below is an example breakdown:
Let's say these are your results:
Platform | Purchased reported |
Meta Ads | 10 |
FERMÁT | 5 |
Here’s why:
FERMÀT only counts the 5 same-session, in-funnel conversions.
Meta includes 5 additional conversions that includes delayed or indirect conversions using its 7-day click / 1-day view attribution window.
Important: They’re both correct — they’re just measuring different behaviors.
What Is the “Halo Effect”?
The Halo Effect in digital marketing refers to the indirect influence your ads have on shopper behavior — even when that behavior doesn’t show up as a direct click-and-buy.
Examples:
A shopper sees your ad on Instagram → later Googles your brand → buys
A user clicks your ad, doesn’t convert, but returns 3 days later to buy
Ads boost brand familiarity, increasing organic or direct traffic
Meta can attribute some of this activity to your ads.
FERMÀT intentionally doesn’t, so you can see only the direct performance of your in-funnel experience.
How-To: Interpret and Use Both
Both attribution models serve valuable purposes in your marketing analytics:
Know what you’re measuring:
FERMÀT gives you a clear, honest picture of immediate performance driven by your funnel.
Meta shows you the broader impact of your ads across time and channel
Use each tool for what it’s best at:
FERMÀT for optimizing funnel design, creative performance, and conversion rate
Meta for understanding retargeting value, long-term campaign ROI, and halo lift
Align your team and clients:
Make sure everyone understands why numbers differ
Use FERMÀT to validate immediate conversion drivers
Use Meta to show how your campaign fits into the larger buying journey
Tip: Think of FERMÀT as measuring the direct effect of your storefront and Meta as capturing the influence your ads have on your full marketing ecosystem.
Remember that discrepancies between Meta and FERMÀT reporting aren't errors, but reflections of their different measurement approaches:
FERMÀT = How well your funnel drives instant purchases
Meta = How your ad campaigns influence behavior over time
Both metrics provide valuable insights that, when used together, offer a comprehensive view of your marketing performance.