The State of Web Vitals

Stylesheet initiator

What injected each stylesheet: parser, script, or inline.

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 Stylesheet initiator

What injected each stylesheet: parser, script, or inline.

4
Categories
In the distribution
49.4%
Fleet share
Top: inline
87.1%
Sites with any
Of inline

3.7% of stylesheets are injected by JavaScript.

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

The stylesheet initiator mix who uses what, and how fast each group loads

Median INP (sites using feature)
0
100ms
200ms
300ms
400ms
500ms
Inline87ms49% of sites
Parser86ms46% of sites
Script93ms4% of sites
Other96ms1% of sites
VariantShare of requestsMedian
Inline
49%
87ms
Parser
46%
86ms
Script
4%
93ms
Other
1%
96ms

Stylesheet initiator. On the fleet: 49.4% inline, 46.4% parser, 3.7% script. 87.1% of sites use at least one inline.

By count inline leads (49.4%); by bytes it is parser (58.9%). computed

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

Passing INP 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
Inline 49.4%
93
93
94
97
97
97
97
95
94
92
Parser 46.4%
91
93
94
95
96
96
97
98
98
98
98
Script 3.7%
95
96
96
93
91
88
92
85
86
92
Other 0.5%
96
94
94
94
93
96
95
98
91
← few of this category on the pagemany →
60%95%+ of sites passing INP 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 INP.

Parser swings the hardest: 91% of sites pass INP with few, 98% with many. computed

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

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

60%70%80%90%100% few → many
Script 3.7% 95% → 92%
Other 0.5% 96% → 93%
Inline 49.4% 93% → 92%
Parser 46.4% 91% → 98%
% of sites passing INP · 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 Script costs the most: the INP pass rate falls from 95% with few to 92% with many. computed

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

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

Script-injected CSS is late CSS. The preload scanner cannot see it, it downloads only after the injecting script ran, and when it finally applies it can restyle content that was already painted. Parser-discovered link tags are known from the first bytes of HTML and download immediately.

Late stylesheets are also a CLS source: content rendered with the early styles jumps when the late sheet lands. If a script must inject styles for a widget, scope them to the widget so the rest of the page cannot move.

How does this affect the Core Web Vitals?

Stylesheet initiator correlates with the LCP. With Other, 87% of sites pass the LCP. With Script, 78% do.

Go fix it Eliminate render-blocking resources → Identify and fix CLS →
Related signals Image dimensions set → Script initiator → Stylesheets per page → Scripts per page → Chrome field data from 94,910 sites, representing millions of real page loads · How we measured