Domain Authority Estimator
Approximating a Score You Can't Look Up Yourself
Domain Authority itself is a proprietary machine-learning score maintained by Moz from its own live link index, so there's no public formula to reproduce exactly. What you can do is build a directional approximation from the three link-graph signals that most heavily influence any authority-style metric: how many unique domains link to a site, the total volume of backlinks, and how long the domain has existed.
The Formula
Referring Domains Factor = min(100, log₁₀(Referring Domains + 1) ÷ log₁₀(100,001) × 100)
Backlinks Factor = min(100, log₁₀(Total Backlinks + 1) ÷ log₁₀(10,000,001) × 100)
Site Age Factor = min(100, (Site Age in Years ÷ 20) × 100)
Score = (Referring Domains Factor × 0.50) + (Backlinks Factor × 0.35) + (Site Age Factor × 0.15)
Backlinks Factor = min(100, log₁₀(Total Backlinks + 1) ÷ log₁₀(10,000,001) × 100)
Site Age Factor = min(100, (Site Age in Years ÷ 20) × 100)
Score = (Referring Domains Factor × 0.50) + (Backlinks Factor × 0.35) + (Site Age Factor × 0.15)
Note: This is an educational approximation only. It is not the actual Moz Domain Authority score, and no calculator without access to Moz's live link index can reproduce that figure exactly.
Where This Estimate Helps
- Rough competitive comparisons — when you know a competitor's referring domain and backlink counts (from any link database) but not their DA, this gives a directional stand-in.
- Tracking your own progress — plugging in updated link counts over time to see whether your link-building trend is moving the estimate up.
- Vetting acquisition targets — a fast sanity check on a domain's link profile before deeper due diligence.
Example Scores
| Referring Domains | Total Backlinks | Site Age | Estimated Score |
|---|---|---|---|
| 100 | 1,000 | 1 yr | 35.8 |
| 1,000 | 10,000 | 3 yrs | 52.3 |
| 10,000 | 100,000 | 7 yrs | 70.3 |
| 50,000 | 1,000,000 | 12 yrs | 86.0 |
| 100,000 | 5,000,000 | 20 yrs | 98.5 |
How to Use This Calculator
- Enter the number of referring domains (unique linking sites).
- Enter the total backlink count across all those domains.
- Enter the site's age in years.
- Select Calculate to see the estimated 0–100 score.
Related Calculations
Once you have a rough authority estimate, score individual link opportunities with the Backlink Value Calculator, or gauge how hard a specific keyword will be to rank with the Keyword Difficulty Calculator.