Domain Authority (DA) vs Page Authority (PA): How Authority Metrics Work and How to Improve Them
If you have spent any time studying Search Engine Optimization (SEO), you have almost certainly encountered two abbreviations that dominate every link-building conversation: DA (Domain Authority) and PA (Page Authority).
Website owners, digital marketers, and domain investors frequently treat these metrics as absolute grades of website quality. However, a widespread misunderstanding exists regarding how authority scores are calculated, how they relate to Google's actual ranking algorithms, and why a high DA score does not automatically guarantee top search engine rankings.
Here is a technical guide explaining the math behind DA and PA, how third-party authority metrics differ from Google's internal PageRank, and actionable strategies to improve your site's authority score legitimately.
SEO Authority Metrics Comparison Matrix
| Metric Name | Provider | Scale Type | Primary Data Source | Used by Google? |
|---|---|---|---|---|
| Domain Authority (DA) | Moz | Logarithmic (1–100) | Root Domain Link Equity Graph | No (Third-party metric) |
| Page Authority (PA) | Moz | Logarithmic (1–100) | Individual URL Backlink Strength | No (Third-party metric) |
| Domain Rating (DR) | Ahrefs | Logarithmic (1–100) | Unique Dofollow Referring Domains | No |
| Authority Score (AS) | Semrush | Compound (1–100) | Backlinks + Organic Traffic + Spam Data | No |
| PageRank (PR) | Internal Algorithmic | Google's Global Web Index Graph | Yes (Core Ranking Signal) |
1. What Is Domain Authority (DA)?
Domain Authority (DA) is a comparative metric developed by Moz that predicts how likely a root domain is to rank in search engine result pages (SERPs). DA is calculated on a 1-to-100 logarithmic scale.
What Does "Logarithmic Scale" Mean in Practice?
Because DA is logarithmic, it is significantly easier to grow a score from DA 10 to DA 20 than it is to grow from DA 70 to DA 80.
- Moving from DA 10 to DA 20 requires a modest number of quality referring domains.
- Moving from DA 70 to DA 80 requires millions of high-equity backlinks from authoritative enterprise domains (such as news outlets, universities, and major portals).
2. Domain Authority (DA) vs. Page Authority (PA): The Key Difference
The distinction between DA and PA comes down to scope:
- Domain Authority (DA): Measures the predictive ranking strength of an entire root domain and all its subdomains (e.g.,
example.com). - Page Authority (PA): Measures the predictive ranking strength of a single specific URL (e.g.,
example.com/blog/seo-guide).
Important SEO Reality: Google ranks individual web pages, not entire domains. A brand-new page on a high-DA site may rank instantly because of inherited internal link equity, but an individual URL on a low-DA site can outrank a high-DA domain if its specific Page Authority (PA) and content relevance are superior.
3. Does Google Use DA in Its Ranking Algorithm?
No. Google does not use Moz Domain Authority, Ahrefs DR, or Semrush Authority Score as ranking factors.
Google representatives have repeatedly confirmed that third-party metrics do not exist in Google's ranking systems. Instead, Google relies on its proprietary, internal implementation of PageRank, alongside hundreds of content quality, relevance, and user experience signals.
Third-party DA scores are comparative indicators—they help webmasters estimate link equity relative to competitors, but manipulating DA through artificial link schemes will not fool Google's ranking algorithms.
4. How to Improve Your Website's Authority Score Leglegitimately
If you want to increase your domain's real search authority and third-party DA score safely, focus on these 4 core strategies:
A. Earn Backlinks from Unique Referring Domains
Getting 100 backlinks from a single domain provides diminishing returns. Receiving 1 backlink from 100 distinct, authoritative root domains builds significantly higher link equity.
B. Eliminate Toxic Spam Links and Low-Quality Directories
High Spam Scores drag down authority metrics. Audit your backlink profile regularly to identify automated spam links, low-quality directory submissions, or PBN (Private Blog Network) links.
C. Build High-Value "Linkable Assets"
Publish content that naturally attracts editorial backlinks: original research studies, free industry tools, infographics, and technical step-by-step guides.
D. Optimize Internal Link Structure
Distribute link equity from your high-PA landing pages to deeper blog posts and product pages using strategic, descriptive anchor text.
Summary
Domain Authority and Page Authority are valuable diagnostic metrics for comparing your link profile against competitors. However, long-term search success requires focusing on what Google actually measures: helpful content, topical authority, clean technical architecture, and natural link equity.
To inspect authority metrics, backlink profiles, and technical SEO parameters, use the XFOX SEO Tools Suite and audit overall domain valuation via XFOX Domain Intelligence.
Frequently Asked Questions (FAQ)
Why did my Domain Authority drop when I didn't lose any backlinks?
Because DA is a comparative logarithmic metric, Moz updates its global link index periodically. If large websites in Moz's index gain millions of links, the relative scale adjusts, causing smaller sites' DA scores to fluctuate slightly without any loss of actual traffic.
What is a "Good" Domain Authority score?
DA is relative. A "good" DA score is simply one that is higher than your direct search competitors in your specific niche.
Do nofollow links increase Domain Authority?
No. Standard logarithmic DA calculations primarily count dofollow links that pass link equity. However, nofollow links still drive direct referral traffic and brand awareness.
