Q* (Q star) is Google's measure of the quality of a document, described in US Department of Justice records of 2025 calls with Google engineers that were filed as exhibits in the search antitrust case. The records describe it as largely static and related to the site rather than the query, with PageRank as one input. The 2024 Content Warehouse leak names several attributes as applied in Qstar. Google has not documented Q* publicly. For a site, it means quality is judged largely at site level and changes slowly.
What is Q*?
Q* is Google's quality score for a document. A DOJ record of a January 31, 2025 call with Google engineer Pandu Nayak, filed as exhibit PXR0357 in the Google search antitrust case, defines it in one line.
A February 18, 2025 call with HJ Kim (PXR0356) calls it page quality and links it to trustworthiness. Unlike T*, which scores relevance to a query, Q* is described as mostly independent of the query.
Q* (pronounced "Q star"), Google's measure of quality of a document
Pandu Nayak, Google (as recorded by the DOJ), January 31, 2025 Call with Google Engineer Pandu Nayak (PXR0357), US Department of Justice
How does Q* work?
The exhibits give only the outline. The Kim record says PageRank is used as an input to the quality score, and the Nayak record says PageRank continues to be one of the factors that goes into the quality signals for pages. The Kim record also discusses quality in the context of the content farm problem.
The May 2024 Content Warehouse API leak adds attribute names. In the CompressedQualitySignals module, siteAuthority is described as "converted from quality_nsr.SiteAuthority, applied in Qstar", lowQuality as "applied in Qstar", and unauthoritativeScore as "one of the web page quality qstar signals".
The leak also contains site-level "chard" attributes in the QualityNsrNsrData module, where chardEncoded is described as a "site quality predictor based on content". The documentation does not say chard feeds Q*, so treat that link as unconfirmed.
What evidence is there that Google uses Q*?
This is trial evidence, supported by the leak. The DOJ records are notes of interviews with named Google engineers, filed as exhibits. They are not Google documentation and do not give formulas or weights.
The leak shows attribute names and short descriptions only. Google told Search Engine Land on May 29, 2024 that people should avoid assumptions based on out-of-context, outdated or incomplete information, so the leak shows that Qstar existed as a label, not how it is weighted today.
Q* (page quality (i.e., the notion of trustworthiness)) is incredibly important.
HJ Kim, Google (as recorded by the DOJ), February 18, 2025 Call with Google Engineer HJ Kim (PXR0356), US Department of Justice
Why does Q* behave like a site-level score?
The Kim record describes Q as largely static and tied to the site. That fits Google's own public statement that site-wide signals exist alongside page-level ranking.
Practical consequence: a few strong pages do not rescue a site whose indexed page set is mostly weak, and improvements show up slowly because the score is not recalculated per query.
This was and continues to be a lot of work but could be easily reverse engineered because Q is largely static and largely related to the site rather than the query.
HJ Kim, Google (as recorded by the DOJ), February 18, 2025 Call with Google Engineer HJ Kim (PXR0356), US Department of Justice
What should a site do about Q*?
Treat quality as a property of the whole indexed set. Remove, consolidate or noindex pages that earn no impressions and add nothing, strengthen trust signals on the pages that matter, and earn links from sources that are themselves trusted, since PageRank is described as an input.
A falsifiable test: track the share of indexed URLs that earn impressions over 16 months in Search Console before and after pruning. If Q* behaves as described, site-wide visibility of the remaining pages should move over months, not days.
Site-wide signals and classifiers are also used and contribute to our understanding of pages.
Google, A guide to Google Search ranking systems, Google Search Central
Which Laurelin audit checks test for Q*?
The new check, a large share of indexed URLs earn no impressions, measures the weight of low-value pages in the indexed set. It is a proxy for a site-level quality score, not a reading of Q*.
Related existing checks:
- Thin content: thin pages are the most common drag on site-level quality.
- Commodity content: content that adds nothing over what already ranks.
- Claims without sources: trustworthiness is how the Kim record characterises Q*.
- No named author: anonymous content weakens trust where authority matters.
- Low referring domain authority vs competitors: PageRank is described as an input to the quality score.
What are the key dates for Google Q* quality score?
- 2024-05-27: iPullRank publishes analysis of the leaked Content Warehouse documentation, including siteAuthority applied in Qstar (source)
- 2024-05-29: Google responds to the leak, cautioning against out-of-context assumptions (source)
- 2025-01-31: DOJ call with Pandu Nayak describing Q*, later filed as PXR0357 (source)
- 2025-02-18: DOJ call with HJ Kim describing Q* as page quality and trustworthiness, later filed as PXR0356 (source)
Frequently asked questions about Google Q* quality score
What is Q* in Google search?
Q* is Google's measure of the quality of a document, described in DOJ records of 2025 calls with Google engineers filed as trial exhibits. It is described as largely static and related to the site rather than the query.
Is PageRank part of Q*?
The DOJ exhibits say PageRank is used as an input to the quality score. They do not say how much weight it carries.
Does the 2024 leak mention Q*?
Yes. Several attributes in the leaked CompressedQualitySignals module, including siteAuthority and lowQuality, are described as applied in Qstar.