What Are Moz, MozRank, Domain Authority (DA), and Page Authority (PA)?

Moz didn't invent the concept of link authority. Google did — with PageRank, the algorithm Larry Page built in 1998 that used the quantity and quality of links pointing to a page as a proxy for its credibility. What Moz did was create a public-facing version of that logic, because Google's actual PageRank score became invisible to practitioners in 2016 when Google stopped updating the public toolbar.

The result was a set of metrics — MozRank, Domain Authority, and Page Authority — that gave SEO practitioners a working framework for evaluating link strength, comparing competitive positions, and making link-building decisions without access to Google's internal data.

These are not Google metrics. They have never been part of Google's ranking algorithm, and Moz is explicit about this. What they are is a standardized, consistently-calculated approximation of link authority that, when used correctly, provides genuinely useful competitive intelligence. The caveat "when used correctly" does real work in that sentence — Moz metrics are widely misunderstood, frequently misused, and occasionally gamed in ways that make them actively misleading to practitioners who take them at face value.

This guide covers what each metric actually measures, how the calculations work, what the limitations mean in practice, and how to use the data to make better SEO decisions rather than worse ones.

Understanding Moz as a Company and Why Its Metrics Matter

Moz was founded in 2004 as an SEO consultancy and evolved into a software platform. Its tools — including the Moz Pro suite, the Link Explorer, and the MozBar browser extension — are used by SEO practitioners, agencies, and in-house marketers to audit sites, research backlinks, and analyse competitive positioning.

The metrics Moz developed emerged from a practical need: practitioners needed a way to evaluate the relative authority of websites and individual pages without access to Google's proprietary signals. Moz built its own web crawler (Mozbot) and its own link index, then applied machine learning models to that data to generate scores that approximated ranking potential.

The key word is approximated. Moz metrics are models — they correlate with ranking performance in aggregate, but they don't determine it. A page with a PA of 62 may outrank a page with a PA of 74. A domain with a DA of 35 may rank above a domain with a DA of 55 for a specific keyword. The scores are directional indicators, not deterministic predictors.

That caveat understood, the metrics are genuinely useful — particularly for comparative analysis, link prospecting, and tracking the trajectory of a site's authority over time.

MozRank — Measuring Link Popularity at the Page Level

What MozRank Measures

MozRank is the oldest of Moz's core metrics and the most directly analogous to Google's original PageRank concept. It measures the link popularity of a specific page — how many external pages link to it and how authoritative those linking pages are.

The score runs from 0 to 10. Most pages that have any external links at all sit in the 1–4 range. Pages with strong, diverse backlink profiles from authoritative domains reach into the 5–7 range. Scores above 7 represent pages with exceptional link authority — the kind that takes years of consistent link acquisition to build.

The Logarithmic Scale — What It Actually Means

MozRank uses a logarithmic scale, which has a practical implication that most introductory explanations mention without making sufficiently concrete.

The difference between a MozRank of 2 and 3 might require 10 additional quality links. The difference between 6 and 7 might require 10,000. The effort required to move the score increases exponentially at each step — not linearly.

This is why focusing on absolute MozRank targets is counterproductive. A site moving from 2.4 to 3.1 in six months may have done significantly more meaningful link-building work than a site moving from 5.8 to 6.0 in the same period — even though the second movement looks larger on the scale.

What Influences MozRank

Volume of inbound links — the raw number of external pages pointing to a given page. Volume matters, but it is the weakest of the three factors.

Authority of linking pages — links from pages with high MozRank pass more equity than links from low-authority pages. A single link from a high-authority news site can contribute more to MozRank than a hundred links from low-traffic blogs. This is the link quality principle that most practitioners understand in theory but frequently ignore in practice when they pursue link quantity.

Domain diversity — a page with 500 links from 10 different root domains has weaker MozRank than a page with 200 links from 200 different domains. Search engines and Moz's models alike treat link diversity as a trust signal — a broad base of linking domains is harder to manufacture than a concentrated one.

Follow vs NoFollow attribute — links with the rel="nofollow" or rel="sponsored" attributes do not pass link equity in Moz's model, consistent with how Google treats them. Only standard followed links contribute meaningfully to MozRank.

Where MozRank Is Useful

MozRank is most useful for evaluating the link strength of specific pages — either your own or competitors'. If you're trying to understand why a competitor's blog post ranks above yours for a target keyword despite what appears to be weaker content, their page's MozRank relative to yours is often part of the answer.

Domain Authority — Estimating the Ranking Potential of an Entire Domain

What DA Measures

Domain Authority is a score from 1 to 100 that estimates how likely a domain as a whole is to rank competitively in search engine results. It is not a measure of any specific page — it aggregates the authority signals of the entire domain into a single number.

Moz calculates DA using a machine learning model trained on Google search results. The model takes in a range of link-based signals and produces a score calibrated to correlate with ranking performance across a broad range of queries.

How DA Is Actually Calculated

The inputs Moz's model uses include:

Total number of linking root domains to the site (unique external domains pointing anywhere on the domain)
Total number of inbound links across all pages
MozRank and MozTrust scores across the domain
The quality distribution of linking domains — how many are themselves high-authority
Spam signals — indicators that the link profile contains artificial or low-quality links

The model is recalibrated periodically as Moz updates its link index and retrains against current Google ranking data. This means DA scores can shift without any change to your site — a recalibration of the model or a change in Moz's crawl coverage can move scores across the board simultaneously.

The Comparative Nature of DA — The Most Misunderstood Aspect

DA is relative. This is the most important characteristic of the metric and the one most frequently ignored.

A DA score of 45 is not good or bad in isolation. Its meaning depends entirely on what your competitors score. In a competitive niche where the top-ranking sites have DA 70–80, a DA of 45 is a significant authority gap. In a local or specialist niche where most competing sites have DA 15–25, a DA of 45 represents a commanding position.

This relativity has a practical implication: the goal is not to reach a specific DA number. The goal is to have higher DA — and more importantly, stronger actual link authority — than the sites you're competing against for specific keywords.

Page Authority — The Page-Level Equivalent of DA

What PA Measures

Page Authority applies the same predictive logic as DA but at the individual page level rather than the domain level. It estimates how likely a specific URL is to rank in search results, on a 1 to 100 scale.

PA is calculated from broadly similar inputs to DA, but scoped to the page: the number and quality of links pointing specifically to that URL, the page's internal linking structure, and the overall authority context of the domain it sits on.

The Relationship Between DA and PA

The relationship between DA and PA is worth understanding precisely because it's often mischaracterised.

A page on a high-DA domain starts with an authority foundation derived from the domain's overall link profile. But it does not automatically have high PA. A page on a domain with DA 72 that has received zero external links and no internal link support may have a PA of 18. The domain authority provides a floor — it doesn't determine the ceiling.

Conversely, a specific page on a moderate-DA domain can have high PA if it has attracted significant external links in its own right. The earlier example in the original article illustrates this correctly: Website A with DA 60 and PA 30 may lose a specific ranking to Website B with DA 40 and PA 45, because the ranking signal for a specific URL competition is PA — not DA.

This distinction matters for content strategy. Publishing a piece of content on a high-DA domain gives it an authority advantage. That advantage is amplified if the content also earns its own external links (raising PA directly) and receives strong internal links from other high-PA pages on the same domain.

When to Use PA vs DA

Use DA when:

Evaluating a site's overall competitive position
Assessing the value of a potential link-building partner
Benchmarking your domain's trajectory over time
Comparing your site against category competitors

Use PA when:

Evaluating whether a specific page can compete for a specific keyword
Identifying underperforming pages that need link support
Assessing a competitor's specific page strength before targeting the same keyword
Deciding which pages to prioritisze for internal linking

How to Apply These Metrics in Practice

Competitor Analysis

The most direct application of Moz metrics is comparing your site's DA and specific pages' PA against the sites ranking in the top positions for your target keywords.

Pull the DA of the top 10 ranking domains for a target keyword. If the range is DA 55–75 and your domain is DA 28, the authority gap is substantial — link building is a prerequisite for ranking on this keyword, and content quality alone will not bridge it. If the range is DA 25–45 and your domain is DA 40, the authority is competitive and content quality, technical SEO, and on-page optimization become the differentiating factors.

This analysis should precede keyword targeting decisions, not follow them. Targeting high-authority keywords with a low-DA domain produces content that Google indexes, occasionally positions in the 40–80 range, and rarely breaks into the first page — regardless of content quality. The effort produces low return.

Link Building Prospecting

When evaluating whether to pursue a link from a specific site, DA provides a quick qualification filter. A link from a site with DA 12 and a spam-heavy link profile offers negligible link equity — potentially negative if Google's spam detection associates your domain with low-quality linking patterns.

A few practical thresholds that work as a starting framework (to be adjusted based on your own domain's authority level):

DA below 20 with poor content quality: not worth pursuing
DA 20–35 with relevant, genuine content: worth considering for topical relevance
DA 35–50: good link prospect, especially if topically relevant
DA 50+: high-value link target — prioritize outreach

Topical relevance matters alongside DA. A DA 38 site in your specific industry niche is typically more valuable than a DA 55 general directory or a DA 60 site with no thematic connection to your content.

Content Prioritization

PA data across your site's pages reveals which pages have the authority to compete and which need investment. A standard content audit using PA should ask:

Which high-PA pages are targeting keywords they're not yet ranking on the first page for? These are conversion opportunities — they have the authority but may need content or on-page improvements.
Which strategically important pages have low PA? These need internal link support from high-PA pages on the same domain — the most efficient way to raise a page's PA without external link building.
Which pages have high PA relative to their content quality or commercial importance? These are authority sources — using them as internal linking hubs toward conversion-focused pages passes equity to where it matters most.

The Limitations That Matter Most in Practice

Understanding Moz metrics correctly requires understanding where they fail — not as a caveat to dismiss them, but as a calibration tool for using them accurately.

DA Is Not a Google Signal

Google has confirmed repeatedly that it does not use DA, PA, or any Moz metric as a ranking factor. These are Moz's approximations of ranking potential, not Google's inputs. A site with DA 15 can and does outrank a site with DA 55 when the lower-DA site has better content, stronger technical SEO, and more relevant topical authority for the specific query.

The confusion between DA and Google's signals is the single most common misapplication of Moz metrics — treating DA improvements as direct ranking improvements when they are, at best, correlated with the link-building activity that produces ranking improvements.

DA Can Be Gamed

This is the limitation most introductory articles skip entirely. Because DA is primarily driven by inbound links from high-authority domains, it is vulnerable to manipulation through purchased links, link schemes, and private blog networks (PBNs) that exist specifically to inflate authority metrics without earning genuine editorial links.

A domain with a DA of 48 built through purchased links may rank poorly and be at constant risk of a Google penalty. A domain with a DA of 35 built through legitimate editorial links in its niche may outperform it consistently and safely.

When evaluating a site's DA — particularly for link-building decisions — look at the link profile composition in Link Explorer, not just the headline score. A domain with DA 45 driven by 3,000 links from 8 different root domains has a fundamentally different profile than a domain with DA 45 driven by 800 links from 600 different root domains.

Scores Reflect Moz's Crawl, Not the Full Web

Moz's link index, while substantial, does not crawl every link on the internet. Links that Mozbot hasn't discovered don't appear in the calculation. This means a site's actual link authority may be higher than its DA reflects — particularly for newer sites or sites with backlinks from pages Moz crawls infrequently.

This also means comparing DA across sites in different categories requires some caution. A site in a niche with many links from pages Moz crawls frequently will be better represented in the index than a site with equivalent genuine authority in a niche with many links from infrequently crawled pages.

Data Lag Creates Temporary Noise

Moz updates its link index on a rolling basis, but there is typically a lag between when a link is published or removed and when DA/PA reflects the change. A significant new backlink may take weeks to appear in the score. A link-building campaign completed three months ago may only now be fully reflected.

This makes short-term DA movements unreliable as performance indicators. DA trend over six to twelve months is meaningful. DA change over two to four weeks is noise.

How to Combine Moz Metrics With Other Data Sources

Moz metrics work best as one input among several, not as a standalone authority indicator.

With Google Search Console: GSC shows actual ranking positions, click-through rates, and impression data for your domain. Moz metrics provide context for why you rank where you rank — a page ranking in positions 8–12 for a target keyword despite strong content may have a PA gap relative to the pages above it, suggesting link building is the appropriate next intervention.

With Ahrefs Domain Rating (DR) and URL Rating (UR): Ahrefs produces analogous metrics using a different link index and a different calculation methodology. When a site's Moz DA and Ahrefs DR are closely aligned, the authority signal is consistent across indices and more reliable. When they diverge significantly — high DA, low DR, or vice versa — it often indicates link profile anomalies worth investigating.

With keyword difficulty scores: Most keyword research tools include a difficulty score that incorporates the DA or DR of ranking pages. This combination of keyword difficulty plus competitor DA provides a realistic competitive assessment before committing content investment to a target.

With actual ranking data: The ultimate validation of Moz metrics is whether the pages and domains with higher DA/PA are actually ranking above yours. If they are, the metrics are calibrating correctly for your niche. If they aren't — if your DA 30 domain consistently outranks DA 55 competitors — your content quality, technical SEO, or topical authority is compensating for the authority gap.

A Practical Decision Framework

Rather than chasing specific DA or PA targets, the most useful application of Moz metrics is as a decision input at three stages:

Before targeting a keyword: Check the DA range of the top 10 ranking domains. If your DA is within 10–15 points of the median, authority is a secondary concern and content quality becomes the differentiating factor. If you're 20+ points below the median, link building is a prerequisite.

Before pursuing a link: Check the potential linking domain's DA and link profile composition. DA above 35 from a topically relevant, editorially genuine site is a reasonable threshold for most link outreach prioritisation.

When prioritising internal linking: Identify your highest-PA pages and use Link Explorer to ensure they're linking toward your highest-value conversion pages. PA flows through internal links — directing it strategically is one of the highest-ROI SEO activities available without external link building.

Key Takeaways

MozRank measures link popularity at the page level — how many links point to a specific page and how authoritative those linking pages are. It is most useful for evaluating individual page link strength in competitive analysis.

Domain Authority estimates the ranking potential of an entire domain on a 1–100 logarithmic scale. It is a comparative metric — meaningful only relative to competing domains, not as an absolute score. It is calculated by Moz, not used by Google, and is vulnerable to inflation through manipulative link building.

Page Authority applies the same predictive logic to individual URLs rather than domains. It is more directly relevant than DA for predicting whether a specific page can rank for a specific keyword — and is the metric to use when evaluating page-level competitive positioning.

None of these metrics should be treated as a direct measure of Google ranking potential. They are useful approximations that become genuinely valuable when used comparatively, in combination with actual ranking data and other SEO metrics, and with an understanding of their limitations — particularly the possibility that high scores can be artificially inflated and that Moz's index does not represent the complete web.

Used correctly, they provide the competitive intelligence framework that makes link-building investment, content prioritisation, and keyword targeting decisions more accurate. Used incorrectly — as absolute scores, in isolation from other data, or as proxies for actual Google authority — they produce false confidence and misdirected effort.

The goal is never to improve the score. The goal is to improve the underlying authority that the score is attempting to measure. Those are related objectives, but they are not the same one.