The State of Web Vitals

LCP image byte weight on Wix sites

60.9% of audited sites (2,411) keep their LCP hero image under 40 KB and pass LCP at 94% (1.2s median), whereas the 0.5% shipping hero images over 300 KB drop to 88% (1.2s median).

Field data PhoneDesktopAll Scope All sites October 2026 edition · All devices field outcomes · Wix sites only
Wix Scoped to 5,623 sites out of 203,892 analyzed (cms) Compare with all sites →

32.3% of Wix sites use an LCP image between 40 and 100 KB LCP image byte weight, and 96% of those sites have a good LCP, against 94% of all Wix sites.

The State of Web Vitals · October 2026 · Wix: 5,621 crawled sites · 5,333 with all devices field data · 3,960 sites with LCP image byte weightBy Arjen Karel · corewebvitals.io/state-of-cwv
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LCP pass rate

Sites with an LCP image between 40 and 100 KB LCP image byte weight have a good LCP most often: 96%, against 94% of all Wix sites. Sites with an LCP image between 100 and 300 KB hero image size have it least often, at 92%.

SitesGood, needs improvement, poor LCPMedian
All Wix sites5,33394%1.2s
40 to 100 KB hero image 32.3%1,20496%1.2s
Under 40 KB hero image 60.9%2,30294%1.2s
100 to 300 KB hero image 6.4%23992%1.2s
Over 300 KB hero image 0.5%1688%1.2s
GoodNeeds improvementPoorSites: with Chrome field data
The State of Web Vitals · October 2026 · Wix: 5,621 crawled sites · 5,333 with all devices field data · 3,960 sites with LCP image byte weightBy Arjen Karel · corewebvitals.io/state-of-cwv
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LCP image byte weight usage

An LCP image under 40 KB is the most used: 60.9% of Wix sites. An LCP image between 40 and 100 KB is 32.3% of Wix sites.

Under 40 KB hero image 60.9% 40 to 100 KB hero image 32.3%
Under 40 KB hero image 60.9% 40 to 100 KB hero image 32.3% 100 to 300 KB hero image 6.4% Over 300 KB hero image 0.5%
The State of Web Vitals · October 2026 · Wix: 5,621 crawled sites · 5,333 with all devices field data · 3,960 sites with LCP image byte weightBy Arjen Karel · corewebvitals.io/state-of-cwv
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The four LCP phases

Across the four LCP sub-parts in Chrome's field data, the largest gap between an LCP image between 40 and 100 KB and an LCP image between 100 and 300 KB sits in time to first byte (TTFB): 406 ms median for an LCP image between 40 and 100 KB against 392 ms for an LCP image between 100 and 300 KB. Overall median field LCP is 1.2s for an LCP image between 40 and 100 KB (TTFB 406 ms, load delay 467 ms, load duration 155 ms, render delay 154 ms) versus 1.2s for an LCP image between 100 and 300 KB.

Median LCP phase breakdown (Chrome field p75) Load delay Median LCP
Wix sites with LCP image byte weight 2,859419 ms458 ms139 ms152 ms458 mslab 458 ms1.2s
Under 40 KB hero image 1,742432 ms454 ms151 ms454 mslab 454 ms1.2s
100 to 300 KB hero image 197392 ms457 ms164 ms160 ms457 mslab 457 ms1.2s
40 to 100 KB hero image 908406 ms467 ms155 ms154 ms467 mslab 467 ms1.2s
TTFB Resource load delay Resource load time Element render delay
The State of Web Vitals · October 2026 · Wix: 5,621 crawled sites · 5,333 with all devices field data · 3,960 sites with LCP image byte weightBy Arjen Karel · corewebvitals.io/state-of-cwv
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LCP image byte weight per framework

On React, 61% of sites use an LCP image under 40 KB LCP image byte weight, and 94% of React sites have a good LCP, against 94% of all sites.

FrameworkLCP image byte weight on its sitesGood LCP
Wix sites with LCP image byte weight 3,960 sitesUnder 40 KB hero image 61%40 to 100 KB hero image 32%94%
React 3,959 sitesUnder 40 KB hero image 61%40 to 100 KB hero image 32%94%
Under 40 KB hero image 40 to 100 KB hero image 100 to 300 KB hero image Over 300 KB hero image
The State of Web Vitals · October 2026 · Wix: 5,621 crawled sites · 5,333 with all devices field data · 3,960 sites with LCP image byte weightBy Arjen Karel · corewebvitals.io/state-of-cwv
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LCP image byte weight or the framework

Does the framework explain the LCP image byte weight difference?

On React, 96% of sites with an LCP image between 40 and 100 KB LCP image byte weight have a good LCP, against 94% of React sites with an LCP image under 40 KB. Within React, sites with an LCP image between 40 and 100 KB have a good LCP more often.

How intrinsic versus rendered megapixels waste hero bandwidth

The median LCP image is 0.23 intrinsic megapixels rendered into a 0.12 megapixel slot. Serving unresized desktop banners to mobile viewports inflates hero transfer bytes and extends LCP load duration. Across 2,411 sites (60.9%) with a hero image under 40 KB, 94% pass field LCP (1.2s median), dropping to 88% (1.2s median) on the 0.5% (18) exceeding 300 KB.

The State of Web Vitals · October 2026 · Wix: 5,621 crawled sites · 5,333 with all devices field data · 3,960 sites with LCP image byte weightBy Arjen Karel · corewebvitals.io/state-of-cwv
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Understanding LCP image byte weight

Compress hero images below 100 KB using AVIF or WebP and serve responsive srcset widths matched to the rendered viewport slot. Across all audited sites, 60.9% keep the hero image under 40 KB (94% good LCP, 1.2s median) versus 0.5% above 300 KB (88% good LCP, 1.2s median).

Go fix it Optimize the LCP image → LCP: resource load duration → Optimize images for Core Web Vitals →
The State of Web Vitals · October 2026 · Wix: 5,621 crawled sites · 5,333 with all devices field data · 3,960 sites with LCP image byte weightBy Arjen Karel · corewebvitals.io/state-of-cwv
Related signals LCP loading attribute → LCP element type → LCP responsive markup → LCP discovery → By Arjen Karel · 5,621 crawled Wix sites (5,333 with all devices Chrome field data, 3,960 sites with LCP image byte weight, October 2026) · How we measured