The State of Web Vitals

Iframes per page

How many iframes the page embeds.

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

At a glance the headline numbers for Iframes per page

How many iframes the page embeds.

0
on the typical site
half of sites sit at or below
2
1 in 4 sites exceed this
the top quarter
8
the heaviest 1%
the long tail
94,748
sites measured
phone field data

The typical page embeds 0 iframes.

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

Distribution & median CLS site count and median CLS at each level of iframes per page

0.00 0.04 0.08 0.11 0.15
0.1
0 26889 53777
0 1 2 3 4 5 6 7–8 >p98
Good (≤0.1) Needs improvement Poor (>0.25) Site count
The State of Web Vitals · Q1 2026 · 94,910 sites · phone field datacorewebvitals.io/state-of-cwv
3

Passing CLS by iframes per page which level passes the CLS most often

Iframes per pageSitesPassing CLSCLS
0 53,777 91% 0.00
1 16,457 87% 0.00
2 11,100 87% 0.00
3 5,386 86% 0.00
4 3,538 84% 0.01
5 1,758 82% 0.01
6 1,026 83% 0.01
7–8 934 81% 0.01
>p98 772 76% 0.02
Good Needs Improvement Poor Faded rows: under 100 sites

Iframes per page 0. p75 2. p99 8. Spearman with CLS r = +0.38. At the low end (0): CLS 0.00. At the high end (>p98): CLS 0.02. computed

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

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

Each iframe is a separate document with its own resources, scripts and lifecycle, and its work still competes for the same device. The count is a decent proxy for embed weight: chat widgets, videos, ad slots, forms.

Every embed should justify itself. The heavy default (always-on iframe) has a light replacement for almost every case: a facade for video and chat, a static image for maps, a reserved slot for ads.

How does this affect the Core Web Vitals?

Iframes correlate with the CLS. With few iframes, 91% of sites pass the CLS. With many, 76% do. The decline is gradual. There is no point where sites suddenly start failing.

Go fix it Chat widgets with perfect Core Web Vitals → Perfect YouTube Core Web Vitals → Speed up a Calendly integration →
Related signals Responsive image markup → Image fetchpriority → Script coverage (used vs unused) → Bytes by resource type → Chrome field data from 94,910 sites, representing millions of real page loads · How we measured