The State of Web Vitals

Compression mix

Text-response compression across requests: brotli, gzip, zstd, or none.

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

At a glance the headline numbers for Compression mix

Text-response compression across requests: brotli, gzip, zstd, or none.

18
Categories
In the distribution
49.6%
Fleet share
Top: none
99.6%
Sites with any
Of none

25.5% of text responses use Brotli. 49.6% ship uncompressed.

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

The compression mix mix who uses what, and how stable each group is

Median CLS (sites using feature)
0
0.10
0.20
0.30
0.40
0.50
None0.0350% of sites
Br0.0326% of sites
Gzip0.0322% of sites
Zstd0.032% of sites
Dcb0.021% of sites
Utf-80.070% of sites
Aws-chunked0.050% of sites
Nosniff0.170% of sites
Deflate0.030% of sites
VariantShare of requestsMedian
None
50%
0.03
Br
26%
0.03
Gzip
22%
0.03
Zstd
2%
0.03
Dcb
1%
0.02
Utf8
0%
Webp, webp
0%
7bit
0%
Avif
0%
Webp
0%
Utf-8
0%
0.07
Identity
0%
Base64
0%
X-gzip
0%
Aws-chunked
0%
0.05
Nosniff
0%
0.17
Deflate
0%
0.03
Identity, compress
0%

Compression mix. On the fleet: 49.6% none, 25.5% br, 21.7% gzip. 99.6% of sites use at least one none.

None leads by count (49.6%) and by bytes (80.1%). computed

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

Passing CLS per bucket every category and count level at once - color is the pass rate

1
2
3
4
5
6
7
8
9
10
11
None 49.6%
82
84
83
82
82
81
80
76
76
75
73
Br 25.5%
77
78
76
76
78
78
74
76
79
83
78
Gzip 21.7%
81
82
80
78
81
79
77
75
74
69
70
Zstd 2.1%
78
77
77
77
76
78
77
71
78
76
Dcb 1.2%
84
86
86
89
86
89
87
86
88
85
83
Deflate 0%
83
81
42
← few of this category on the pagemany →
60%95%+ of sites passing CLS Faded cells: under 100 sites

Each row is a category, each column its own count bucket (few on the left, many on the right); the cell is the share of those sites passing CLS.

Gzip swings the hardest: 81% of sites pass CLS with few, 70% with many. computed

The State of Web Vitals · Q1 2026 · 94,910 sites · desktop field datacorewebvitals.io/state-of-cwv
4

Few vs many - does quantity cost CLS? the pass rate with few vs many of each category

60%70%80%90%100% few → many
Gzip 21.7% 81% → 70%
None 49.6% 82% → 73%
Zstd 2.1% 78% → 76%
Dcb 1.2% 84% → 85%
Br 25.5% 77% → 78%
% of sites passing CLS · hollow ring = pages with few, solid dot = pages with many

Per category: the pass rate among pages with FEW of it (hollow ring) against pages with MANY (solid dot), worst trend first. Thin buckets are excluded from the endpoints.

More Gzip costs the most: the CLS pass rate falls from 81% with few to 70% with many. computed

The State of Web Vitals · Q1 2026 · 94,910 sites · desktop field datacorewebvitals.io/state-of-cwv
5

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

HTML, CSS, JavaScript, SVG and JSON shrink to a fraction of their size with gzip or brotli. Every CDN can apply it at the edge. An uncompressed HTML document delays the TTFB. An uncompressed stylesheet delays rendering, and with it the LCP.

Compression cuts transfer time, not execution time. A compressed JavaScript bundle still costs the same CPU to parse and run, so compression helps TTFB and LCP, not INP. Also check the right files: images, video and woff2 fonts are already compressed. The gains are in your text responses.

How does this affect the Core Web Vitals?

Compression mix correlates with the LCP. With Dcb, 97% of sites pass the LCP. With Zstd, 85% do.

Go fix it Configure Cloudflare for passing the Core Web Vitals →
Related signals Scripts per page → Stylesheet origin (1P/3P) → DOM depth → Responsive image markup → Chrome field data from 94,910 sites, representing millions of real page loads · How we measured