If the conversion counts in Google Ads or Meta don't match reality in your store, it's no accident. Three forces — Safari ITP, ad-blockers and iOS restrictions in general — systematically eat into your data. Here's how big those losses usually are and how server-side tracking can recover most of them.
Three sources of loss
1. Safari ITP and cookie lifetime
Intelligent Tracking Prevention (ITP) is Safari's mechanism for limiting cross-site tracking. For measurement it has one major effect: cookies set by JavaScript in the browser (classic client-side tracking) have their lifetime capped at 7 days — and in some cases just 24 hours.
What that means in practice: a customer arrives from an ad, browses a product and buys it 10 days later. If the cookie expired in the meantime, at checkout they look like a direct/organic visitor and the ad never gets credit for the conversion. For longer purchase cycles, that can be a large share of conversions.
2. Ad-blockers
Ad-blockers and tracking blockers block the Google Analytics, Meta Pixel, TikTok and other scripts directly. Depending on the source, 20–35% of users run an ad-blocker — more among technical audiences. Their activity never shows up in client-side measurement at all.
3. iOS and restrictions in general
iOS has steadily strengthened privacy — from App Tracking Transparency to Private Relay, which hides the IP address. Each such layer chips away at the accuracy of client-side measurement.
How big the losses are
The exact figure depends on your traffic mix, but a typical store with a normal share of mobile and Safari traffic sees tens of percent fewer conversions in client-side measurement than actually happen. The larger the iOS share and the longer the purchase cycle, the bigger the gap.
How server-side tracking gets them back
Server-side tracking addresses all three sources of loss at once:
- Against ad-blockers: data flows through your own (sub)domain, not through known tracking domains. To an ad-blocker it looks like an ordinary request to your site, so it isn't blocked.
- Against ITP: the identification cookie is set by the server via an HTTP header as first-party. Such cookies are not subject to the 7-day cap that applies to JavaScript-set cookies — their lifetime can be considerably longer.
- Against iOS restrictions: conversions are sent server-to-server via official APIs (Measurement Protocol, Conversions API) that are designed to work even without a reliable client-side environment.
Cookie Keeper helps too
On top of the server-side setup you can extend cookie lifetime even further with the Cookie Keeper feature, which keeps visitor identifiers consistent even in environments that aggressively clear cookies. See the docs: Cookie Keeper — extending cookie lifetime.
How to measure the loss yourself
- Compare the number of orders in your store with conversions in Google Ads / Meta for the same period. The difference is a rough estimate of the loss.
- Check the share of Safari and iOS in Google Analytics — the higher it is, the bigger the ITP impact.
- After deploying server-side, watch the match rate in Meta Events Manager and the conversion count in Google Ads — you typically see an increase over the first few weeks.
Summary
ITP, ad-blockers and iOS aren't a temporary problem — they're the permanent direction browsers have taken. Client-side measurement will only cope worse over time. Server-side tracking with first-party cookies is the most effective defense: it recovers conversions you'd otherwise never see and improves ad optimization at the data level. Try DataNostro for free or read the complete guide to server-side tracking.