Google Chrome's cookie phase-out has begun: What you need to know

Benoit Le Gendre

Data and Adtech Strategy Lead

8th January 2024

~ 5 min read

Starting 4th January 2024, Chrome will block third-party cookies for 1% of users globally.

The cookie crunch has started and marketers are bracing themselves for what will be one of the key topics of this year. With an estimated 65% browser market share globally, Google Chrome has laid out a clear timeline over the past years for third-party cookie tracking, following the lead (and it’s important to remember this) of other browsers following both increasing privacy concerns from users and increasing regulatory pressure. 

Starting 4th January, Google Chrome released a new feature called Tracking Protection that will block third-party cookies for 1% of randomly selected users globally. An increase to 100% of users is expected from Q3 2024. The ramp up to 100% of users is subject to addressing any remaining competition concerns of the UK's Competition and Markets Authority (CMA).

What are the expected impacts of this first move toward cookie deprecation for marketers and advertisers?

The cookie depreciation is going to force major changes in how digital advertising works, especially for programmatic advertising. 

This first phase of cookie deprecation provides a critical period for websites and marketers to measure the impact of third-party cookie deprecation and prepare for the next big step toward the end of 2024.

Web developers and sites should audit cookie usage now and prepare for the broader rollout by reviewing key actions outlined by Google here

How will this impact current campaigns?

The 1% deprecation is probably too modest for it to have a direct impact on performance and reach of campaigns. That said we can expect the below impact: 

  • Campaign reach and frequency - Measuring reach and ad exposure will become more challenging, especially across devices
  • Conversion volume - Conversion volume may start decreasing as ability to measure users across sites decreases 
  • Targeting accuracy - Campaigns that rely on aggregated third-party data are going to see lower audience volumes and targeting accuracy will decrease over time.

What solutions are being developed and how can marketers use them?

Google’s answer to the deprecation of third-party cookies is the Privacy Sandbox, which has been in development for some time but is also under the scrutiny of authorities in the context of competition and global market position. 

Privacy Sandbox represents an alternative pathway that Google is providing for the ad industry to take, relying on anonymised signals (that are not cookies). Advertisers will use APIs to receive aggregated data about conversion (how well their ads performed) and attribution (which entity is credited, say, for a purchase). Google will obviously build integration to its advertising platforms to allow for what we can expect to be an almost seamless transition to the new cookie-less world. Below we have outlined 3 key actions for marketers to take. 

1) Create new strategies to increase first-party data collection and activation 

First-party data collected by advertisers is becoming essential to improve targeting accuracy and build a profile of users visiting your site:

  • Build strategies that look to increase user data collection across user journey on site 
  • Review customer data tools you have in place and how this data can be easily and instantly activated in your marketing campaigns
  • Build new strategies to increase use of first-party data across your marketing campaigns.

2) Adopt new ways to measure true incrementality from your marketing activity 

One of the key elements to the Privacy Sandbox is the expected integration with Google Marketing Platform, especially Display & Video 360, which will allow it to bring solutions to advertisers in a seamless way. That said, measurement is expected to be more challenging moving forward. Croud has built a solution to understand the true incrementality of your marketing activity

  1. Understand channel-level incrementality by leveraging platform solutions such as brand and search lift studies or set A/B test as a starting point
  2. Understand the cross-channel impact by leveraging causal proof studies
  3. Understand portfolio incrementality using media mix modelling to support your forward budget and strategy planning 

3) Expand your marketing reach via Digital Out Of Home (DOOH) or Connected TV 

Whilst we can expect reach to be affected for traditional prospecting and remarketing campaigns, programmatic buying has evolved in recent years to integrate exciting new opportunities in marketing plans such as DOOH or connected TV that don’t rely directly on cookies:

  • DOOH provides the ability to run marketing campaigns that can have precise geo-targeting up to a global reach level across multiple cities around the world, making this approach well suited for a large share of advertisers. 
  • Connected and smart TV represent a key opportunity to increase reach and experiment with new and impactful creative format and messages.

The great news is that Display & Video 360 allows you to do this from your laptop in an easy and straightforward way, whilst bringing you advanced measurement and frequency capabilities across your existing portfolio of campaigns.


Google is committed to the deprecation of third-party cookies this year, but not without solutions such as the Privacy Sandbox in place for advertisers to leverage. In short:

  • Websites and publishers should use this first half of the year to test and measure the impact of the cookie deprecation and implement key fixes where needed, especially when websites functionality is affected.
  • On the other end, advertisers should build robust first-party data strategies that form an integral part of their marketing strategy across all channels and allow for quick and systematic activation.
  • Marketers and analysts should work closely together to use new measurement tools such as causal proof studies, and take the opportunity to explore new strategies leveraging DOOHH or make full use of the potential of connected TV.

If you are looking to understand the true incrementality of your marketing activities and are not afraid to ask the hard questions, please reach out to us.

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