The definitive explainer

How is Domain Authority calculated?

Moz Domain Authority isn't a simple sum of your backlinks — it's the output of a machine-learning model that predicts how well a site is likely to rank. Here's exactly what goes into the score, why it's on a 1–100 logarithmic scale, and how to move it.

8-min read Reviewed by Pawan Kumar, SEO Specialist Beginner-friendly

Quick answer

Domain Authority is calculated by a Moz machine-learning model that predicts how likely a website is to rank in Google search results. The model weighs your backlink profile most heavily — the number of unique referring domains, the quality and authority of those links, your total backlinks, and your spam score — then scores you from 1 to 100 on a logarithmic, comparative scale. Because it's relative to the rest of the web, DA is a prediction of ranking strength, not a direct count of your links.

Start here

What Domain Authority actually is

Domain Authority (DA) is a search-engine ranking score developed by Moz that runs from 1 to 100 and predicts how likely a website is to rank in search results. A higher DA signals a stronger, more trusted backlink profile relative to other sites.

The key word is predicts. DA does not measure your rankings directly, and it is not a number Google uses. Instead, Moz built a model trained on real search results, then asked: "given this site's link profile, how would a site like this tend to rank?" The answer, scaled to 1–100, is your Domain Authority.

The inputs

What goes into the DA calculation

Moz weighs dozens of link-based signals, but four factors do most of the work. These are the levers that move your score.

Highest weight

Linking root domains

The number of unique websites that link to you. This is the single strongest input — fifty links from fifty different domains count for far more than fifty links from one site.

High weight

Link quality & authority

A link from a strong, trusted, relevant domain passes more authority than a link from a weak or unrelated one. Quality consistently beats quantity.

Medium weight

Total number of backlinks

The overall count of links pointing to your site. It matters, but only alongside diversity and quality — raw volume on its own moves the needle very little.

Drags it down

Spam score

Moz estimates how "spammy" your link profile looks. Toxic links from low-quality domains raise this score and pull your DA down — the opposite of what cheap link buying promises.

The takeaway: DA rewards a diverse, high-quality, low-spam backlink profile. That's also exactly what genuinely helps you rank on Google — which is why building DA the right way is never wasted.

Under the hood

The machine-learning model behind your score

Here's the part most explanations skip. Moz doesn't add up your links with a fixed formula. It uses a machine-learning model trained against actual Google search results. The model learns which link patterns tend to appear on sites that rank well, then estimates where your site fits.

Two consequences follow from this, and they explain almost every confusing thing about DA:

1. DA is comparative. Your score is graded relative to every other site Moz tracks. If competitors earn strong links and you stand still, your DA can fall even though nothing on your site changed. This is the most common reason a DA suddenly drops.

2. DA gets recalculated. Each time Moz refreshes its index or retrains the model, scores shift across the whole web at once. Small fluctuations after an update are normal and industry-wide — not a sign of a problem.

The scale

Why DA uses a 1–100 logarithmic scale

DA is logarithmic, which means each point higher is harder to earn than the last. Climbing the bottom of the scale is quick; climbing the top is slow.

0–20Easy to move
20–40Moderate
40–60Harder
60–80Hard
80–100Very hard
Effort to gain each point: lowEffort to gain each point: very high

In practice this means moving from DA 20 to DA 30 is far easier than moving from DA 70 to DA 80. A new site can climb the lower range quickly with a focused link-building campaign, while top-tier sites need enormous authority just to hold position. It's also why a realistic, valuable target for most businesses is DA 40+ — credible and competitive, without the diminishing returns of chasing 80.

Factor by factor

Each factor — and how to improve it

A quick-reference table of what the model weighs and the white-hat way to influence it.

FactorImpact on DAHow to improve it (white-hat)
Unique referring domainsVery highEarn links from many different real, relevant, indexed sites.
Link quality / authorityHighPrioritise links from trusted, high-authority domains over volume.
Total backlinksMediumGrow links naturally alongside diversity — never bulk-buy.
Spam scoreNegativeAvoid link farms and PBNs; disavow toxic links you didn't earn.
Anchor text diversitySupportingKeep anchors varied and natural rather than over-optimised.
Link relevanceSupportingSeek links from sites topically related to your niche.

Want the full playbook? Read how to increase Domain Authority for the step-by-step method — or let us do it for you.

Don't confuse them

DA vs PA vs Ahrefs DR — calculated differently

Three authority metrics, three separate calculations. They measure related things but aren't interchangeable.

MetricMade byWhat it scoresHow it's calculated
DA (Domain Authority)MozWhole-domain ranking strengthML model on your full backlink profile, 1–100 logarithmic.
PA (Page Authority)MozA single page's ranking strengthSame Moz model, applied to one URL instead of the domain.
DR (Domain Rating)AhrefsBacklink-profile strengthBased purely on the quantity and strength of referring domains.

This service focuses on Moz DA, the most widely recognised authority metric across the SEO industry.

Check it yourself

How to see your calculated DA (free)

You can't run Moz's model yourself, but you can read its output for any domain in seconds.

1

Moz Link Explorer

Moz's own free tool reports your official Domain Authority, Page Authority and spam score for any domain.

2

Free DA/PA checkers

Many third-party DA/PA checkers pull the same Moz score, handy for quick competitor comparisons.

3

Ask us for a free check

Send your URL on WhatsApp and we'll tell you your current DA and the realistic gap to 40+.

The honest part

Does the DA number itself matter to Google?

We'll always be straight with you about what this score does and doesn't do.

Is DA a Google ranking factor?

No. Domain Authority is a Moz metric, and Google has confirmed it doesn't use the DA number to rank pages. DA is a third-party prediction of ranking strength, not an input to Google's algorithm.

So why does the calculation matter?

Because the very signals the DA model rewards — quality, diverse, low-spam backlinks — are the same signals that genuinely influence Google rankings. Improve the inputs the right way and you raise your DA and your real ranking power together.

Where a higher DA helps right now

Winning client trust, qualifying for paid guest posts and ad networks, reselling SEO credibly, and benchmarking against competitors. For most businesses, DA 40+ is the threshold that signals an established, trustworthy site.

Put the formula to work

Improve every factor — reach DA 40+

We build the exact signals Moz's model rewards: diverse, high-authority, low-spam white-hat backlinks. You get a verifiable before/after Moz report — and if your DA doesn't reach 40+ in 14–21 days, you get a full refund.

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FAQ

How DA is calculated — common questions

Straight answers to what people ask about the score behind the score.

How is Domain Authority calculated?

Moz calculates DA with a machine-learning model that predicts how likely a site is to rank in search results. It weighs your backlink profile — unique referring domains, link quality, total backlinks and spam score — and outputs a score from 1 to 100 on a logarithmic, comparative scale.

Is there a formula I can use to calculate DA myself?

No fixed formula exists, because DA comes from a machine-learning model, not a simple equation. You can only read the output from Moz Link Explorer or a DA checker — you can't recreate the calculation by hand.

What is the most important factor in DA?

The number of unique linking root domains, combined with their quality. Many links from many different trusted, relevant sites move DA far more than a large number of links from few sources.

Why is DA on a logarithmic scale?

So the score reflects how the web actually works: authority is concentrated at the top. A logarithmic 1–100 scale makes moving from 20 to 30 much easier than 70 to 80, mirroring how much harder real authority is to earn at the high end.

Does Google use Domain Authority in its calculation?

No. DA is a Moz metric and is not used by Google. However, the backlink signals the DA model rewards are the same signals that genuinely influence Google rankings, which is why building DA correctly still helps you rank.

How often is DA recalculated?

Moz periodically refreshes its index and model, and scores shift across the whole web each time. Minor fluctuations after an update are normal and industry-wide, so a small change rarely means anything is wrong with your site.

Keep reading

Related Domain Authority guides

Now that you know how DA is calculated, here's how to read it, grow it, and troubleshoot it.

Understand it. Now grow it.

We build the exact backlink signals the Moz model rewards — and take your DA to 40+ in 14–21 days, or your money back.

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