Are Chrome Third-Party Cookies Staying? What Google's Privacy Sandbox Retirement and a PNAS Study Mean for Ad Revenue (2026)
How Google confirmed that Chrome keeps third-party cookie choice and retires many Privacy Sandbox technologies, based on Google's official blog, plus the PNAS field experiment showing a 29.1% drop in publisher ad revenue without cookies.
"Third-party cookies are disappearing from Chrome" has been the biggest variable in advertising since 2020. Google chose to keep them instead, and has also dropped many of the Privacy Sandbox technologies it built as replacements. This article summarizes the current state and the effect on ad revenue, based on Google's official announcement and a study published in PNAS in May 2026. App-side measurement changes are covered separately in our ATT opt-in guide and SKAdNetwork explainer.
What Google has officially said
Google's Privacy Sandbox blog (October 17, 2025, Anthony Chavez) builds on the earlier announcement that Chrome will maintain its current approach to third-party cookie choice, and says Google gathered ecosystem input to decide what happens to each API. The key point is that several technologies are being retired because of low adoption.
Technologies being retired
The official blog lists:
- Attribution Reporting API (Chrome and Android)
- IP Protection and On-Device Personalization
- Private Aggregation (including Shared Storage)
- Protected Audience (Chrome and Android) and Protected App Signals
- Related Website Sets, SelectURL and SDK Runtime
- Topics (Chrome and Android)
Google said it will phase them out following Chrome and Android processes and share updates on its developer site's status page. Timing differs by feature, so check each API's status page.
Technologies that continue
The same post says CHIPS and FedCM have seen broad adoption, including support from other browsers, and will continue. Private State Tokens will be maintained and Google will explore more approaches to reduce fraud and abuse. For measurement, Google pointed to the interoperable Attribution standard under discussion in the W3C Private Advertising Technology Working Group.
| Item | Status | Note |
|---|---|---|
| Third-party cookies | User-choice approach kept | No new standalone prompt; can be blocked in settings |
| Topics, Protected Audience, etc. | Retired | Low adoption cited |
| CHIPS, FedCM | Kept | Supported by other browsers too |
| Private State Tokens | Kept | Anti-fraud use |
| Attribution | W3C standard discussion | Google says it will collaborate |
How much ad revenue is lost without cookies?
The paper "Can privacy technologies replace cookies? Ad revenue in a field experiment", published in PNAS vol. 123, no. 19 in May 2026, analyzes an industry-wide field experiment overseen by Google and the UK CMA. Chrome users were randomly assigned to third-party cookies enabled, cookies disabled, or the Privacy Sandbox replacing cookies. It covers more than 200 million ad impressions across over 5,000 publishers worldwide.
Experiment results
| Item | Result |
|---|---|
| Publisher ad revenue with cookies blocked | Down 29.1% |
| Share recovered by the Privacy Sandbox | 4.2% of the loss |
| Scale | 200M+ impressions, 5,000+ publishers |
The authors note that the 4.2% figure reflects adoption and performance observed during the study and may reflect modest industry adoption. They also report that privacy-preserving auctions increase ad latency, reducing impression delivery and limiting revenue. The result is consistent in direction with Google's decision to retire the technologies, but the paper does not itself explain Google's reasons, so it should not be read as proof of cause.
What this means for bloggers and publishers
Display ad revenue such as Google AdSense depends partly on user-identification signals. The experiment shows revenue can fall sharply when cookie signals disappear, so rather than reacting to every policy headline, it is safer to:
- Grow visit sources that depend less on any one ad signal, such as search.
- Keep your privacy policy and ad consent notices current.
- Check official channels, such as Google and the W3C Attribution discussions, regularly.
Summary
Chrome's third-party cookies remain a user choice for now, and many Privacy Sandbox technologies meant to replace them are being retired. Since no deadline is set, check any article claiming one against the official blog.
FAQ
Are third-party cookies going away in Chrome in 2026?
Google said Chrome will maintain its current approach of offering users third-party cookie choice. No phase-out date is set, and users can block them in settings.
Is the Privacy Sandbox completely over?
No. Retirement of Topics, Protected Audience, Attribution Reporting and others was announced on October 17, 2025, but CHIPS, FedCM and Private State Tokens continue.
How much ad revenue is lost without cookies?
In the PNAS field experiment, publisher ad revenue fell 29.1% in the cookie-blocked group, and the Privacy Sandbox recovered only 4.2% of it.
What should bloggers do to prepare?
Grow traffic from sources like search, and keep consent notices and your privacy policy up to date.