Aggregated Event Measurement
- Also called AEM, Meta's attribution for iOS 14 and later
- Updated October 28, 2026
Aggregated Event Measurement (AEM) is Meta's way of measuring website and app conversions from people on iOS 14 and later devices. It strips identifiers, adds noise and aggregates the data across people before Meta uses it to deliver ads and report results. For website campaigns it now runs automatically: the old setup of ranking eight events per domain is gone.
How does Meta define Aggregated Event Measurement?
Meta's About Meta's Aggregated Event Measurement page:
Meta's Aggregated Event Measurement is a protocol that allows for the measurement of web and app events from people using iOS 14 and later devices. Aggregated Event Measurement processing includes privacy protective measures like removing identifiers, adding differential privacy, and aggregating the data across users before personalizing ads we show and measuring how they perform.
For websites, Meta says it "helps us recover limited measurement of website conversions from people using iOS 14.5 and later devices." Meta's app pages use another name for it: "Meta's attribution for iOS 14 and later, also known as Aggregated Event Measurement". In Events Manager, the app eligibility check sits in a section called "Meta's attribution for iOS 14+".
The page's one dated line covers app partners: "As of October 9, 2024, we are sending Aggregated Event Measurement (AEM) reporting to mobile measurement partners (MMPs)".
Do you still need to configure 8 events per domain?
No. The about page lists what changed for website conversion campaigns:
| Before | Now, in Meta's words |
|---|---|
| Rank 8 conversion events per domain | "You no longer need to prioritize 8 conversion events per domain for web conversion optimization" |
| Turn on value sets for value optimization | "you don't need to turn on value sets in order to use value optimization" |
| The AEM tab in Events Manager | "has been removed because you no longer need to configure your web events" |
| Verify your domain | "You aren't required to verify your website domains for purposes related to event configuration" |
| Pick a conversion domain in Ads Manager | "You don't need to select a conversion domain when you create a campaign" |
The summary line: "Now, there are no steps you need to take for your events to be processed through Aggregated Event Measurement." Meta's iOS 14.5 campaigns page agrees: "There are no actions you need to take to use Aggregated Event Measurement for website campaigns." Domain verification may still matter for other reasons, which the about page notes.
The changes come with rollout wording, "Here are the changes you'll see when you have access", so an older account may still show the previous setup.
How does AEM work for app campaigns?
Apps still have a step. AEM covers "sales campaigns with catalog turned on or off, lead campaigns and engagement campaigns" when the destination is an app, and "It's currently not supported for custom event optimization." It now extends to the app promotion objective, which "means you can now run app promotion campaigns without configuring app events for Apple's SKAdNetwork."
You may need to confirm eligibility first. Meta's eligibility
page says you "may be
required to verify that your app events are eligible" in Events Manager, under
the dataset's Settings tab, Check app eligibility.
Why does AEM reporting differ from SKAdNetwork?
They are two attribution methods counting different things. Meta's reporting differences page says AEM "provides near real-time reporting, while SKAdNetwork reporting has delays of at least 24 hours", and AEM "works within Meta's technologies, while SKAdNetwork attributes conversions across different ad networks". The windows differ too: AEM app installs use a 1-day, 7-day or 28-day click setting, while SKAdNetwork credits an install "within 30 days". Low volume and the first days after launch widen the gap.
What it means for your ads
- Don't rebuild the old event ranking. For website campaigns there is nothing to configure. If Events Manager still shows the AEM tab, your account likely hasn't had the update yet.
- iOS results pass through aggregation and noise, so expect some gap between Ads Manager and your store. The attribution setting you choose shifts the count further.
- Retargeting pools can shrink. Meta's iOS page says website and app custom audiences "may decrease" in size and suggests "using a broad audience for inclusion", which is what Advantage+ audience does.
- Value optimization needs no extra switch. Meta's requirements page says "You don't need to turn on maximize value of conversions for events sent through Aggregated Event Measurement." See maximize value of conversions.
Common mistakes
- Assuming the Conversions API skips AEM. Meta: "Events sent to Meta via the Conversions API may also be processed in accordance with limits set by Aggregated Event Measurement."
- Comparing AEM and SKAdNetwork in the first days of a campaign. Meta says to "Allow a few days for the data to become stable before making comparisons."
Sources
- About Meta's Aggregated Event Measurement — Meta Business Help Center (accessed October 28, 2026)
- Reach people using iOS 14.5 or later with Meta ads — Meta Business Help Center (accessed October 28, 2026)
- How to check if your app events are eligible for Aggregated Event Measurement — Meta Business Help Center (accessed October 28, 2026)
- Ads Manager reporting differences between Meta's Aggregated Event Measurement and Apple's SKAdNetwork — Meta Business Help Center (accessed October 28, 2026)
- Requirements to use Maximize value of conversions — Meta Business Help Center (accessed October 28, 2026)
Meta rolls AEM changes out by account and revises these pages without notice, so check the source before acting on any of it.
Terrads makes the ads and leaves your events alone: feed, post and story sizes from your brand kit, each laid out for its frame, for the broad audience Meta suggests on iOS.