Google Lighthouse Versions: What Changed from Release to Release
Lighthouse changes several times a year. Most releases are small, but a major version can move scores: a metric gets a new weight, an audit disappears, a category is added. Knowing what changed helps explain why a score moved when your site did not. Every PerfoMetrix report records the Lighthouse version that produced it.
The early years
- 2016: Lighthouse launches as a Chrome extension for auditing progressive web apps, then becomes a panel in Chrome DevTools and the engine of PageSpeed Insights.
- Version 6 (2020): the Core Web Vitals era begins. Largest Contentful Paint, Cumulative Layout Shift and Total Blocking Time join the performance score.
- Version 8 (2021): the weights are reworked. Total Blocking Time counts for 30% and Cumulative Layout Shift for 15%; Time to Interactive’s share shrinks to 10%.
Version 10 (February 2023)
- Time to Interactive no longer counts towards the performance score.
- Cumulative Layout Shift rises from 15% to 25% of the score. The weights since then: FCP 10%, Speed Index 10%, LCP 25%, TBT 30%, CLS 25%.
- Every origin on a page is classified as first or third party.
Version 11 (August 2023)
- More accessibility (axe) checks, and the accessibility audits are re-weighted.
- The legacy navigation mode is removed.
Version 12 (April 2024)
- The PWA category is removed, following Chrome’s updated installability criteria.
- SEO is reorganised: being crawlable can now fail the SEO category on its own; viewport and font-size checks move to best practices; the plugins and tap-target checks leave SEO (tap targets become the accessibility check for target size).
- Performance diagnostics report their estimated savings per metric (LCP, FCP).
Version 13 (October 2025)
- Performance insights replace many older audits. Lighthouse now shares its analysis with the Performance panel in DevTools: render-blocking, image delivery, cache lifetimes, LCP breakdown and document latency are “insights”.
- Several audits are removed, among them third-party facades, offscreen images, font-size, passive event listeners, document.write and font preloading.
- Accessibility weights are adjusted.
Version 13 updates in 2026
- 13.1 (April): a Baseline check tells you which web platform features a page uses that are not yet supported across major browsers.
- 13.2 (April) and 13.3 (May): a new agentic browsing category for AI agents that read and act on pages, with an llms.txt check and WebMCP audits.
- 13.4 (June–July): the agentic browsing category becomes available in the PageSpeed Insights API.
- 13.5 (September): checks for agent resource discovery (ARD) join llms.txt in an agent discovery group.
- 13.6 (October): more accurate simulated loading and bulk URL testing from the command line.
What this means for your score
- Compare like with like. A score from Lighthouse 12 and one from Lighthouse 13 can differ even when the site didn’t change. Our reports name the version used.
- Watch the metrics, not only the score. LCP, CLS and TBT are stable definitions; the overall score depends on the weights of the day.
- Real-user data stays the reference. Lab scores move with tool versions; Chrome UX Report field data reflects what visitors experienced.
Source: the Lighthouse changelog and release notes on GitHub (GoogleChrome/lighthouse) and Chrome’s documentation on performance scoring.