B
Evidence Grade B
Graded
accuracy verified by the review judge
Safe to Cite
Recent
8.4%
8.4% -- conversion lift from 0 1s speed improvement for retail websites (2025)
A 0.1-second speed improvement produced an 8.4% conversion lift on retail websites.
Attribution:
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Lighthouse Research Team
Last verified:
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Source verified
Evidence graded
Value
8.4%
Unit
Percentage
Data Vintage
2025
Entity
Sample Size
30,000,000
Evidence Quality
B
Strong, reliable evidence
Sourced from a well-regarded research firm or industry leader with transparent methodology and a reasonably large sample.
Single source - not yet corroborated
Score breakdown
Extraction
75
Source Trust
60
Citation Chain
20
Independence
30
Methodology
45
Freshness
95
Source
Google and Deloitte
Primary
Tier B
https://kirro.io/how-to-optimize-conversion-rate ↗
Source Article
How to optimize conversion rate (data-backed)
To optimize your conversion rate, start with your value proposition, then simplify your copy, speed up your pages, remove form friction, and test every change. That’s the order. Not because it sounds nice, but because research across 20,000+ pages shows these five areas have the biggest impact, in t…
Original Research
Google and Deloitte
· Original study ↗
Methodology
Google and Deloitte test across 30 million sessions on 37 brand websites
Methodology documented
Segmentation
Industrymarketing
Cite this stat
Plain Text
retail websites: 8.4% conversion lift from 0 1s speed improvement. Source: Google and Deloitte (2025). Via Lighthouse Intelligence -- https://lighthousedata.io/data/google-deloitte-speed-retail-lift-8-4
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<blockquote cite="https://lighthousedata.io/data/google-deloitte-speed-retail-lift-8-4" style="border-left:3px solid #2563eb;padding:12px 16px;margin:16px 0;font-family:system-ui,sans-serif;background:#f0f4ff;"><strong>8.4%</strong> -- conversion lift from 0 1s speed improvement for retail websites<br><small>Source: Google and Deloitte (2025) · <a href="https://lighthousedata.io/data/google-deloitte-speed-retail-lift-8-4" target="_blank" rel="noopener">Lighthouse Intelligence</a></small></blockquote>
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