How Site Strength works

Learn how Rankfield calculates Site Strength from web graph ranks, and how to compare and interpret scores.

#What the score measures

Site Strength combines two standard ranks of each domain in the web graph: PageRank and harmonic centrality. Both rise when many domains link to a domain, and when the domains linking to it are themselves well linked.

Rankfield turns the two rank positions into a logarithmic scale and maps them to 0–100 with a calibration checked against held-out data. The mapping only goes up: a better rank never gives a lower score.

#Read it correctly

• Compare scores within the same release. Every answer is scored with the release in Get Dataset Status.
• Treat a difference of a few points as noise. The score summarises a graph model.
• The score is not a probability, a share of the web or a count of backlinks.
• It does not measure traffic, rankings, relevance or trust.
• It is not interchangeable with Moz Domain Authority, Ahrefs Domain Rating or any other vendor's score: they use other data and methods.

#Which domains have a score

Only domains in the current web graph release, about 118 million. Others answer 200 with "inGraph": false and a siteStrength of 0: the domain isn't in our link graph yet, so treat it as no data, not a score. The field is absent for every other domain, and a malformed domain gets 400. A domain can be missing because the crawl data the graph is built from has no page linking to it, not because it has no links. Coverage and dates has the details.