Lighthouse category scores
also called Non-CWV Lighthouse scoresSEO and accessibility scores
Definition
The eight further Lighthouse figures collected alongside the Core Web Vitals: SEO, accessibility, best practices, Time to Interactive, Total Blocking Time, First Contentful Paint, Speed Index, and the mobile score.
How it's calculated
Each figure is read straight from its own summary measure over the pages in scope, with no derivation on top. The four score-type figures arrive as fractions between nought and one and carry an explicit display contract: multiply by a hundred and round to a whole score point, presented without a percent sign, so 0.925 is shown as 93. The four timing figures arrive in seconds. None of the eight is graded.
Scope, grain and dimensions
- Grain
- One number per figure per date range.
- Dimensions
- device
- Required filters
- date_range
- Aggregation
- Seven of the eight are plain averages of their per-row values across the pages in scope. The mobile score is the exception: it is impression-weighted in the semantic layer, dividing the sum of score times impressions by the sum of impressions.
- Metric type
- score · two scales: SEO, accessibility, best practices and the mobile score are 0-to-1 score fractions; Time to Interactive, Total Blocking Time, First Contentful Paint and Speed Index are seconds
Data sources
Where you'll see this
Named reports that normally include this metric.
Skills and analyses that use it
Skills carry the judgment; the analysis verbs do the reading.
Skills
Analysis verbs
site_health_cwv_check
Method rungs and levers
This sits on the bottom rung: if it reads badly, every measurement above it is unreliable.
levers L1 Technical & crawl health
Ask Quattr
- "What is our accessibility score?" Simulate this →
- "How does our SEO audit score look?" Simulate this →
How to read it
The wider audit that sits beside page experience without being part of it. None of the eight is graded and none feeds the page-experience verdict, so they are context for a conversation rather than inputs to one, and because the set spans two scales, a figure quoted without naming which of the eight it is cannot be read at all.
Caveats, freshness and failure modes
Returned as raw averages and deliberately NOT graded. There is no good, needs-improvement or poor band for any of the eight; assigning one invents a threshold the product does not have.
Two scales in one set. Four are score fractions between nought and one, four are seconds, they are never comparable to each other as numbers.
The score-type figures must be shown as whole score points, not as percentages: the raw fraction is multiplied by a hundred and rounded, with no percent sign. Rendering 0.93 as 0.93% or as 93% are both wrong.
Opt-in: they are only fetched when explicitly requested, and are absent from a default page-experience read.
The mobile score is aggregated differently from the other seven, impression-weighted rather than a plain average, so the set is internally inconsistent in how it rolls up.
First Contentful Paint's direction is still contested between the two shared oracles: one reads a rise as a regression, the other as an improvement. Do not paint a movement in it green or red.
These are lab measurements, not field data from real visitors; collection cadence varies by site and by page.
- Freshness
- varies by site, priority URLs can run nightly; most pages far less often. The collection date rides on the card rather than being assumed.
Common failure modes
- Grading these against Core Web Vitals bands, or presenting one as good or poor.
- Rendering a score fraction as a decimal percentage instead of a whole score point.
- Comparing the mobile score against the other seven as if aggregated the same way, or comparing a score against a timing figure.
- Treating a movement in one of these as a Core Web Vitals regression.
Not the same as
The confusions that cause the most wrong decisions.
Lighthouse category scores Performance score Compare definitions →
The performance score is graded and drives the overall verdict; these eight are ungraded and drive nothing. The performance score also shares the 0-to-1 scale of four of them, which is exactly why the two are confused.
Lighthouse category scores Vital grade Compare definitions →
There is no grade for any of these eight. Presenting one as good or poor invents a band the product does not have.
Related metrics and workflows
Verification
A definition is the smallest part of this.
The measurement matters because something acts on it. Here is the rest of the showcase, in the order most people find useful.