The same website will show a domain authority of 58 and a domain rating of 71, and buyers reasonably ask which one is right. Both are. They are different companies' estimates, built from different link indexes with different formulas, and neither is a number Google has.
What each one actually measures
Domain Authority (Moz)
A 1–100 prediction of how well a domain will rank, trained by Moz against real search results. It draws on Moz's link index and a set of link-quality features. Because it is a trained prediction, DA can move when Moz retrains the model even if nothing about your site changed.
Domain Rating (Ahrefs)
A 1–100 measure of backlink profile strength, based on the quantity and strength of unique linking domains. It is more mechanical than DA: it describes the link graph rather than predicting ranking outcomes.
Why the numbers differ so much
- Different indexes. Each company crawls the web independently, so they know about different links.
- Different treatment of nofollow. The two tools weight non-followed links differently, which alone can shift a score by ten points.
- Different goals. DR describes link strength. DA predicts ranking. A site with a strong link profile and weak content can score high on DR and lower on DA.
- Both are logarithmic. Moving from 20 to 30 is easy. Moving from 70 to 80 is enormously harder. Treating the scale as linear leads to badly wrong value judgements.
The mistake that matters most
Both scores are computed from links, which means both can be manipulated by acquiring links. Neither reads your content, checks whether anyone visits, or knows if your traffic collapsed last quarter.
This is why a site can show a domain rating of 70 and receive almost no organic traffic. Someone built the link profile. The rest of the site never followed.
The reliable tell is the relationship between authority and traffic. High authority with negligible traffic is the signature of a built profile. Check them together and the illusion disappears.
How to use them properly
- Use them to filter, not to decide. A minimum threshold usefully narrows a list of hundreds. It should never be the reason you buy.
- Read both. A large gap between DA and DR is informative in itself and worth a closer look.
- Always pair with traffic and spam score. Authority without traffic, or authority with a high spam score, are both warnings.
- Check the date. A domain rating fetched fourteen months ago describes a site that may no longer exist in that form. Every metric on BlogReach carries its fetch timestamp for this reason.
- Weight relevance above both. A DA 35 site squarely in your niche routinely outperforms a DA 65 general site.
Why we combine signals instead of picking one
Because any single vendor number can be gamed, BlogReach's Reach Authority score combines thirteen signals across Moz, Ahrefs, Semrush, registry data and traffic, weights current evidence fully, and holds missing evidence at a neutral baseline rather than treating it as zero. Every result shows how much of the score is backed by current data, so a thin profile never looks like a complete audit.
You can run any published site through Reach Authority and see the per-signal contribution and the timestamp on each one.
The short version
Trust neither number on its own. Use DR to gauge link profile strength, DA to gauge ranking likelihood, and treat a mismatch between authority and traffic as the most informative signal either one gives you.