The State of Web Vitals

Responsive image markup

Responsive markup on images: srcset / picture vs plain img.

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

At a glance the headline numbers for Responsive image markup

Responsive markup on images: srcset / picture vs plain img.

3
Categories
In the distribution
68.6%
Fleet share
Top: none
89.1%
Sites with any
Of none

68.6% of images ship without responsive markup.

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

The responsive image markup mix who uses what, and how fast each group loads

Median LCP (sites using feature)
0
0.5s
1s
1.5s
2s
2.5s
3s
3.5s
4s
None1.4s69% of sites
Image1.5s23% of sites
Picture1.4s9% of sites
VariantShare of sitesMedian
None
69%
1.4s
Image
23%
1.5s
Picture
9%
1.4s

Responsive image markup. On the fleet: 68.6% none, 22.9% image, 8.5% picture. 89.1% of sites use at least one none.

Lowest-share bucket: LCP 1.3s. Highest-share bucket: LCP 1.4s. r = +0.39.

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

Passing LCP 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
12
None 68.6%
86
85
87
86
87
88
88
87
86
85
85
83
Image 22.9%
88
84
83
83
82
83
82
84
85
88
90
Picture 8.5%
85
90
88
93
91
92
88
89
90
92
88
89
← few of this category on the pagemany →
60%95%+ of sites passing LCP 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 LCP.

No category moves the LCP pass rate much, however many a site ships. 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 LCP? the pass rate with few vs many of each category

60%70%80%90%100% few → many
None 68.6% 86% → 83%
Image 22.9% 88% → 90%
Picture 8.5% 85% → 89%
% of sites passing LCP · 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 None costs the most: the LCP pass rate falls from 86% with few to 83% 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

srcset exists because devices disagree about pixels. A plain img serves the same file to a small phone and a 5K display: too many bytes for one, too few pixels for the other. Responsive markup lets the browser pick per device, and on the hero image the saved bytes are LCP bytes.

Responsive markup still needs width and height for the CLS side: srcset picks the file, the dimensions reserve the box. Most CMSs generate the candidates automatically. The gaps are hand-written templates.

How does this affect the Core Web Vitals?

Of the 3 categories, Picture separates passing sites from failing sites the most. Where Picture is rare: 85% pass the LCP. Where it is common: 90%.

Go fix it Optimize images for Core Web Vitals → Fix layout shift from auto-sizing images →
Related signals Stylesheet origin (1P/3P) → DOM size → Image format mix → Media source → Chrome field data from 94,910 sites, representing millions of real page loads · How we measured