What Is Domain Authority?

Domain authority is a third-party score, typically 0–100, that predicts how likely a whole domain is to rank in search. It is calculated by SEO tools from backlink data — Google does not publish or use it.

Every SEO tool has its own version — Moz's Domain Authority, Ahrefs' Domain Rating, Semrush's Authority Score — and they all attempt the same thing: compress a domain's link profile into one comparable number. The scale is logarithmic, so climbing from 20 to 30 is ordinary work and climbing from 70 to 80 is a different sport.

What it measures is roughly the quantity and quality of domains linking to you, weighted by how authoritative those linking domains are themselves. That makes it a decent proxy for competitive strength and a poor proxy for anything else. It knows nothing about your content quality, your relevance to a specific query, or your technical health.

Its honest use is comparative. Checking whether the sites on page 1 sit far above you tells you whether a keyword is realistic this quarter; watching your own score creep up over a year tells you your link acquisition is working. Chasing the number for its own sake is how teams end up buying links that raise a third-party metric and do nothing for traffic.

The practical play is to use authority as a filter, not a goal. Compare your score against the actual page-1 competitors for a keyword — not against the biggest site in your industry — and pick targets where the gap is small enough to close with a better page. Relevance beats raw authority more often than the score suggests: a niche site with a 30 regularly outranks a 70 on a query it is genuinely about.

Examples

• A new site sits at DA 8 while page 1 for its target keyword averages DA 65 — that keyword is a year-two target, not a launch target.
• A 200-article industry blog at DA 34 outranking a DA 78 news publisher on a technical query, because the whole domain is about that topic.
• A score jumping ten points in a month with no traffic change — usually a link-network artefact or a tool recalculation, not a real gain.