What Is Domain Authority?

The Credit Score of Websites

Domain Authority (DA) is a number between 1 and 100 that predicts how highly a website will rank in Google search results. The higher your DA, the better your chances of appearing on the first page of search results.

DA was created by the SEO tool company Moz. It's not an official Google metric — Google doesn't share its ranking scores. Instead, Moz built DA by studying which website features tend to go along with high-ranking sites. Think of it like a credit score: it's not the bank, but it tries to predict how trustworthy you look.

A site with DA of 80 is considered very strong. A brand-new site often starts around DA 1. It takes time, effort, and good backlinks to climb that ladder.

Why People Obsess Over That Number

Domain Authority matters because it's a fast way to size up a website. Before guest-posting on a blog, buying a link, or partnering with a site, people check DA to decide if it's worth their time. A DA of 5 and a DA of 50 look very different in Google's eyes.

It also helps you track your own progress. If you're consistently building links and creating good content, your DA will tick upward over months and years. It's one signal among many, but it's an easy shorthand for "is this site growing?"

The Three Things That Drive Your DA

Domain Authority isn't magic — it's math based on three main inputs. Here's what Moz's algorithm weighs:

• Linking root domains — How many different websites link back to yours? One link from 100 different sites beats 100 links from the same site.
• Link quality — A link from a major newspaper or university carries far more weight than a link from a spammy directory. Quality over quantity is the rule here.
• Your site's overall authority — Sites with high DA pass along more "ranking power" when they link to you. A link from a DA 90 site is worth much more than a link from a DA 10 site.

The DA scale is logarithmic, not linear. Going from DA 20 to DA 40 is easier than going from DA 60 to DA 80, because the scale compresses at the high end. Most small business sites sit between DA 10 and DA 40.

Checking a Site's DA With an API

Here's a simple example using a JavaScript function to calculate a simplified DA score based on root domains and backlinks. In the real world, Moz's API handles this calculation for you — but the logic shows how the factors combine:

// Simplified Domain Authority estimator
function estimateDA(stats) {
  const { rootDomains, totalLinks, avgLinkDA } = stats;

  // Weight root domains more than total links
  const domainScore = Math.log10(rootDomains + 1) * 20;
  const linkScore = Math.log10(totalLinks + 1) * 8;
  const authorityScore = avgLinkDA * 0.5;

  // Combine and cap at 100
  const raw = domainScore + linkScore + authorityScore;
  return Math.min(Math.round(raw), 100);
}

const mySite = {
  rootDomains: 45,
  totalLinks: 320,
  avgLinkDA: 35
};

console.log("Estimated DA:", estimateDA(mySite));
// Output: Estimated DA: 49

This is a simplification — Moz's real formula involves many more signals — but it captures the core idea: more linking domains and higher-quality links push your score up.

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