The State of Web Vitals

HTTP protocol

The HTTP protocol of the HTML document response.

Field data PhoneDesktopAll Scope All sites Q2 2026 edition · All devices field outcomes
Metric LCP INP CLS
1

At a glance the headline numbers for HTTP protocol

The HTTP protocol of the HTML document response.

3
Categories
185,477 sites
61.5%
Top share
h2
0.00
Top CLS
Median for h2

23.6% of HTML documents arrive over HTTP/3.

The State of Web Vitals · Q2 2026 · 189,915 sites · all devices field datacorewebvitals.io/state-of-cwv
2

HTTP protocol who uses what, and how stable each group is

Median CLS
0
0.05
0.10
0.15
0.20
0.25
h20.0062% of sites
h30.0024% of sites
http/1.10.0015% of sites
VariantShare of sitesMedian
h2 114,133 sites
62%
0.00
h3 43,712 sites
24%
0.00
http/1.1 27,632 sites
15%
0.00

Little daylight between the groups: every variant sits near 0.00 median CLS. computed

The State of Web Vitals · Q2 2026 · 189,915 sites · all devices field datacorewebvitals.io/state-of-cwv
3

Passing CLS per HTTP protocol which group passes the CLS most often

VariantSitesPassing CLSCLS
H3 23.6% 43,712 89% 0.00
H2 61.5% 114,133 88% 0.00
Http/1.1 14.9% 27,632 86% 0.00
Good Needs Improvement Poor Sorted best-passing first · median colored by its own rating · pass = good CLS (0.1 at p75) · one value per site

No variant stands out: pass rates sit between 86% and 89%. computed

The State of Web Vitals · Q2 2026 · 189,915 sites · all devices field datacorewebvitals.io/state-of-cwv
4

Why this matters for the Core Web Vitals, and where to start fixing it

The protocol decides how expensive a connection is. HTTP/3 sets up in fewer round trips and a lost packet no longer stalls everything behind it, which TCP-based protocols suffer from. The document request is where this matters most: it is the first request of the visit and it carries the whole TTFB.

There is a catch on the very first visit. Browsers often discover HTTP/3 support through a header on a previous response (Alt-Svc), so the first document fetch can still pay the older protocol's price. DNS HTTPS records fix that discovery, and your CDN controls whether they exist.

Go fix it TTFB: connection duration → Configure Cloudflare for passing the Core Web Vitals →
Related signals Uncompressed text responses → HTML size (kB) → Connection hints → ETag present → Chrome field data from 189,915 sites, representing millions of real page loads · How we measured