The State of Web Vitals

HTML compression

Compression on the HTML document: brotli, gzip, or none.

Field data PhoneDesktopAll Scope All sites Q1 2026 edition · All devices field outcomes
Metric LCP INP CLS
1

At a glance the headline numbers for HTML compression

Compression on the HTML document: brotli, gzip, or none.

7
Categories
94,906 sites
47.1%
Top share
gzip
86ms
Top INP
Median for gzip

28.5% of HTML documents are Brotli-compressed. 19.4% ship raw.

The State of Web Vitals · Q1 2026 · 94,910 sites · all devices field datacorewebvitals.io/state-of-cwv
2

HTML compression who uses what, and how fast each group loads

Median INP
0
100ms
200ms
300ms
400ms
500ms
gzip86ms47% of sites
none86ms19% of sites
br87ms29% of sites
zstd89ms5% of sites
deflate103ms0% of sites
VariantShare of sitesMedian
gzip 44,671 sites
47%
86ms
none 18,403 sites
19%
86ms
br 27,056 sites
29%
87ms
zstd 4,736 sites
5%
89ms
deflate 34 sites
0%
103ms

Little daylight between the groups: every variant sits near 86ms median INP. computed

The State of Web Vitals · Q1 2026 · 94,910 sites · all devices field datacorewebvitals.io/state-of-cwv
3

Passing INP per HTML compression which group passes the INP most often

VariantSitesPassing INPINP
Deflate 0% 34 100% 103ms
Gzip 47.1% 44,671 96% 86ms
Br 28.5% 27,056 95% 87ms
Zstd 5% 4,736 93% 89ms
None 19.4% 18,403 93% 86ms
Good Needs Improvement Poor Sorted best-passing first · median colored by its own rating · pass = good INP (200ms at p75) · one value per site

No variant stands out: pass rates sit between 93% and 96%. computed

The State of Web Vitals · Q1 2026 · 94,910 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 HTML document is the first thing the browser reads, and the sooner the markup arrives, the sooner the preload scanner can discover everything else: the stylesheets, the fonts, the LCP image. Brotli and gzip shrink HTML to a fraction of its raw size. None means the visitor downloads every byte of markup before the page can even start discovering resources.

Brotli compresses tighter than gzip and every major CDN offers it. This is a switch, not a project.

How does this affect the Core Web Vitals?

HTML compression correlates with the LCP. With Br, 86% of sites pass the LCP. With Zstd, 80% do.

Go fix it Configure Cloudflare for passing the Core Web Vitals → Compression mix →
Related signals HTTP protocol mix → Connection hints → Cache strategy mix → Uncompressed text responses → Chrome field data from 94,910 sites, representing millions of real page loads · How we measured