What is Domain Authority?
Domain Authority (DA) is a metric between 1 and 100 invented by Moz, meant to predict how likely a domain is to rank compared with others. It is calculated primarily from the link profile - how many websites link to you, and how strongly linked those sites are themselves. Rival tools run their own variants on their own scales, such as Ahrefs' Domain Rating (DR).
The most important thing first: Domain Authority is not a Google metric. Google has repeatedly stated that it uses no such domain score - the number is a third party's estimate based on its own link index, not a window into the algorithm. It does not measure your ranking; it models a probability.
Used properly, it is still useful: as a comparative value against direct competitors and as a trend over time. The scale is logarithmic - getting from 20 to 30 is considerably easier than from 70 to 80. Taken in isolation, a single number says almost nothing: DA 35 is strong if your competitors sit at 25 and weak if they sit at 60.
Why does Domain Authority matter?
Domain Authority is the textbook case for the difference between measured and modelled numbers: enquiries and rankings are facts, DA is a tool vendor's calculation rule. Treating it as a goal rather than a comparison instrument means optimising for a model - at worst with bought links that endanger real rankings instead of improving them.
Domain Authority in practice
- 01Before launching a content push you record the DA of the five competitors ranking for your money keywords - the realistically beatable ones are those in your own league.
- 02A guest post enquiry is not judged by DA alone but by whether the site has real traffic and topical proximity - an off-topic DA 60 link delivers less than a DA 30 link from your industry.
- 03Your domain's DA climbs from 18 to 26 within a year while two relevant keywords move from page 3 to page 1 - the trend confirms the link work is taking hold.
