Cookies per site
Cookies set during a cold visit: how many and their total size.
At a glance the headline numbers for Cookies per site
Cookies set during a cold visit: how many and their total size.
The typical site sets 2 cookies.
Distribution & median CLS site count and median CLS at each level of cookies per site — n
Passing CLS by cookies per site — n which level passes the CLS most often
Cookies per site — n 2. p75 5. p99 21. At the low end (0): CLS 0.02. At the high end (>p98): CLS 0.05. computed
Distribution & median CLS site count and median CLS at each level of cookies per site — size
Passing CLS by cookies per site — size which level passes the CLS most often
Cookies per site — size 0 KB. p75 0 KB. p99 2 KB. At the low end (0 KB): CLS 0.02. At the high end (>p98): CLS 0.05. computed
Why this matters for the Core Web Vitals, and where to start fixing it
The cookie count is a proxy. It tells you how many vendors run on the page. Most cookies exist for tracking and each tracker sets its own. The count grows with every tag the marketing stack adds. Cookies are also sent with every request to their domain, which adds header weight. That is rarely the real cost.
The real cost is what the cookies stand for. The vendors behind them run script on your main thread and delay every interaction (INP). They also inject banners, widgets and ads after the page looks settled (CLS). A rising cookie count means it is time to audit the tag manager, not to shrink cookies.
How does this affect the Core Web Vitals?
Cookie size correlates with the LCP. Where the cookie size is low, 89% of sites pass the LCP. Where it is high, 70% do. Cookie size has little causal relationship with the LCP. That makes a high cookie size more likely a result or an indication of a slow, heavily built site than a cause of a slow one. More cookies almost always means more trackers, more third parties and more script, and those do slow pages down.
Chrome field data from 189,915 sites, representing millions of real page loads. How we measured.