TL;DR: Leave it on, and write down your numbers first. From November 12, Meta can match an ad view to an order on the shopper's own device, so your reports may show more conversions with no change in sales. Before the date, export Meta's purchases next to your real orders, day by day. If the two drift apart after November 12 and you can't explain it, switch the setting off per pixel in Events Manager.
What Meta changed
Meta added a setting to the Meta Pixel called Measure conversions on customer devices. Its Help Center article explains the problem with an example. Someone sees your ad for a lamp on Instagram, visits your website two days later and buys it. Meta may hold the ad view and receive the order event, but in its words it "can't always connect them".
With the setting on, the match happens on the customer's device, which holds both the ad view and the order. The match uses "information they already shared with you (like an email) and temporary, non-identifying device information". Meta says it only receives two things: confirmation of the sale, and the campaign to credit.
The same article states that the setting is on by default.
Where the November 12 date comes from
Neither Help Center article carries a date. The date sits in Events Manager, under the switch: "Measurement starting November 12, 2026." Advertisers and the trade press reproduced that line, and the email Meta sent in mid-October, from October 18 onward. Open your own pixel settings to read the line for yourself.
Which sites it applies to
Meta's two articles set three conditions.
| Condition | What Meta's article says |
|---|---|
| Where the shopper is | "Not active for people located in the EU and UK" |
| How the pixel sits on the site | Directly on your page, "not inside an iframe or as an image-only (img) pixel" |
| How people use your site | "Your website must require people to log in to an account using an email or mobile phone number" |
The first condition follows the shopper. A French brand selling to the United States qualifies for its American visitors. A US brand does not qualify for its visitors in Germany.
The third condition is the narrow one. Read as written, a store where anyone can buy as a guest does not qualify. Meta does not say how it checks this, or whether an email typed at checkout counts as a login.
What changes in your reports, and what does not
| Before November 12 | From November 12, setting on | |
|---|---|---|
| Where the match happens | On Meta's servers | On Meta's servers and on the shopper's device |
| Conversions in your reports | Those Meta can connect on its servers | Those, plus the ones matched on the device |
| Attribution window and model | Your current settings | Unchanged |
| Pixel and Conversions API | Running | Running, the setting "doesn't replace" them |
Meta's sentence on attribution is the one to keep. The setting changes which conversions Meta can measure, not how it credits them to your ads.
Expect more conversions and a lower cost per acquisition in Ads Manager on the eligible share of your traffic. Your shop sold the same number of orders. Meta now connects more of them to an ad.
Meta gives two reasons to keep the setting on: you "see more of the conversions you drive in your campaign reporting", and you "improve campaign performance with a stronger signal". The second reason suggests that delivery uses the extra conversions. Meta's articles do not say how.
What Meta has not said
- Leads: the articles describe purchases only. They do not name lead or sign-up events.
- Order value: Meta receives confirmation of the sale. The articles do not say whether the order value travels with it, so the effect on ROAS is unknown.
- Duplicates: the articles do not explain how Meta reconciles a device match with a Conversions API event for the same order.
- Consent: the articles do not mention consent banners. They leave one duty with you: keeping prohibited information out of your integration.
What to do before November 12
This section is my reading, not Meta's guidance.
- Record a baseline: export Meta's purchases and your store's paid orders, by day, for the last 30 days. Keep the ratio between the two.
- Mark the date: add a note for November 12 in every report you send. Do not compare cost per order across that date without it.
- Keep the Conversions API running: Meta says the setting works alongside your setup. Nothing in the articles makes server events optional.
- Check the events after the date: the Meta Ads Data Advisor extension shows what your pixel fires on each page.
- Watch the ratio through Black Friday: if Meta's count rises and your orders stay flat, measurement changed and sales did not. The Black Friday checklist has the morning checks for the sale itself.
How to switch it off
The switch works per pixel. Meta's steps:
- Open Meta Events Manager.
- Click Data sources.
- Select the name and ID of your pixel.
- Click Settings.
- Below the Meta Pixel settings section, find Measure conversions on customer devices and turn it off.
Meta's article says the setting is "on by default for eligible pixels, but you can turn it off at any time". If you manage more than one pixel, repeat the steps for each one. No launch tool shows this switch, Adsap included.
Three cases where switching it off is the cautious choice:
- You are mid-test: a test that started before November 12 needs one way of counting until it ends.
- Your sector has privacy rules of its own: in health or finance, ask whoever owns privacy before a new measurement path runs on customer devices.
- Your numbers stop matching: Meta's count drifts from your orders and you can't find the reason.
Frequently asked questions
A Meta Pixel setting in Events Manager. With it on, Meta matches an ad view to an order on the shopper's own device, using information the shopper already gave your business, such as an email. Meta says it only receives confirmation of the sale and the campaign to credit.
Yes. Meta's Help Center says it is turned on by default for eligible pixels and that you can turn it off at any time. The line under the switch in Events Manager reads Measurement starting November 12, 2026.
No. Meta says your attribution window and attribution model do not change. The setting affects which conversions Meta can measure, not how it credits them to your ads.
No. Meta says the setting works alongside your existing Pixel and Conversions API setup and does not replace it. Keep your server events running.
No. Meta's articles say the setting is not active for people located in the EU and UK. The rule follows the shopper's location, so a European brand still qualifies for its visitors elsewhere.
Sources
Both Meta pages read on 10 November 2026. Meta's Help Center pages carry no update date.
- Meta Business Help Center, About measuring conversions on customer devices: the lamp example, the default, the EU and UK exclusion, the attribution sentence.
- Meta Business Help Center, How to turn on measuring conversions on customer devices: the two requirements and the steps.
- The line "Measurement starting November 12, 2026" in the Meta Pixel settings of Events Manager, and Meta's email to advertisers of mid-October 2026. Advertisers and the trade press reproduced both from October 18, 2026. Meta's Help Center pages do not state the date.