Definition: Domain Authority, or DA, is a score created by Moz that estimates the relative ability of a domain or subdomain to appear in search results. It uses a scale from 1 to 100 and supports website comparisons, but it is neither a Google metric nor a factor that Google’s systems use directly to rank results.
The score is a comparative prediction, not an absolute measure of quality, traffic or visibility. Its meaning depends on the sector, the competitors being assessed and the data available to Moz at each update.
What Domain Authority measures
Domain Authority summarises the estimated strength of a site’s link profile relative to other domains. A higher score indicates a greater predicted ability to compete, but it does not guarantee that a particular page will rank for a specific query.
The metric applies to a domain or subdomain. Page Authority, also developed by Moz, uses a similar scale to estimate the ability of an individual page. Both scores differ from PageRank and from the internal signals used by Google.
DA does not replace other performance metrics such as organic clicks, impressions, conversions or rankings. A domain can gain traffic without an immediate score change, while a DA movement may result from changes to Moz’s index or model.
How it is calculated
Moz calculates Domain Authority with a machine-learning model trained to predict the presence of domains in search results. The exact formula is not public and may evolve, but it uses data from Moz’s link index and combines multiple signals.
Important inputs include linking domains, the quantity and quality of links and the overall structure of the profile. The scale is logarithmic: moving between high values generally requires proportionally more growth than moving between low values.
The score is also relative. If the index adds new websites and links, or if other domains grow faster, a site’s value may change even when that site has made no changes. It is therefore useful to examine the historical trend against a stable set of competitors.
What it is used for
The main use of Domain Authority is SEO comparison. The score provides context when it is assessed alongside the queries, pages and link profiles that explain each website’s performance.
- Competitors: it supports comparisons between domains competing in the same market or set of search results.
- Links: it helps put potential backlink sources into context, together with topical relevance, editorial quality and real traffic.
- Development: it can show changes in the relative strength of a link profile over time.
- Research: it may complement an audit by an SEO agency, without replacing performance and crawl data.
A high DA alone does not make a website a good link source. Relevance, traffic origin, page type, editorial placement and possible manipulation patterns provide a fuller picture than an isolated score.
How to check and compare the score
The official Domain Authority value is available through Moz tools such as Link Explorer, MozBar, Domain Overview and the Moz API. Different index updates can produce score changes, so comparisons should use data collected on similar dates.
Other platforms provide their own metrics. Ahrefs uses Domain Rating, Semrush uses Authority Score, and Majestic combines Trust Flow with Citation Flow. These scales examine related aspects, but their sources, formulas and purposes differ and they are not exact equivalents of DA.
Several criteria support a useful interpretation:
- Same market: compare websites that compete for similar audiences and queries.
- Same tool: avoid combining values from different providers as though they formed one scale.
- Same date: obtain the scores within a comparable time window.
- More indicators: assess DA with referring domains, links, rankings, traffic and conversions.
What can change Domain Authority
DA commonly changes when Moz detects movements in the link profile, updates its index or modifies the calculation model. Gaining or losing links and referring domains may have an effect, but the result depends on their quality and on how the rest of the websites in the scale evolve.
Work intended to improve organic presence may affect the score when it generates genuine link signals. Related actions include:
- Linkable content: publish original and useful resources that other websites choose to cite.
- Diverse references: earn editorial links from different relevant domains.
- Link reclamation: identify lost links, unlinked mentions and broken resources that can legitimately be restored.
- Profile review: examine artificial or low-quality patterns without assuming that every weak link needs removal.
- Combined monitoring: interpret DA alongside organic results and the website’s objectives.
Increasing Domain Authority should not become an independent objective. A sustainable strategy focuses on improving the website and its ability to earn legitimate links; the score can then serve as a comparative reference for that development.