Ahrefs vs Semrush for Backlinks: Which Index Should You Trust?

← All guides · 11 min read · Published July 2026

TL;DR:

• Semrush publishes the bigger raw index (43+ trillion backlinks, 390M referring domains); Ahrefs publishes 35 trillion external backlinks across 210M domains with fresh data every 15 minutes.
• Domain Rating (DR) is a pure link-graph metric — it ignores traffic, spam signals, and content quality by design. Authority Score (AS) is a compound metric that folds in estimated organic traffic and six spam checks.
• A DR 50 and an AS 50 are not the same thing and can't be converted. Different formulas, different inputs.
• When the tools disagree, don't average the scores — open the raw referring-domain data in both and check organic traffic. Disagreement is usually the diagnosis, not the problem.
• For vetting paid placements, DR is the industry's quoting standard, so verify it yourself; AS is a useful second opinion precisely because it's harder to inflate with links alone.

How we evaluated

We compare backlink tools the same way we vet the links they measure — against published, checkable facts rather than reputation:

• Published index numbers. Both companies state their index sizes publicly. We quote those numbers as claims each vendor makes about itself, not as independently audited figures — no third party can verify a trillion-link index.
• Update transparency. How often does each vendor say its backlink data refreshes, and where is that stated?
• Metric documentation. Does the vendor explain what its authority score counts and — just as important — what it deliberately ignores?
• Fitness for link vetting. Can the tool answer the questions that matter before you pay for a placement: real referring domains, real organic traffic, and outbound-link patterns? That's the same standard we apply in our guide to checking backlink quality.

Ahrefs vs Semrush backlink comparison at a glance

Both prices are the vendors' published rates at the time of writing; both companies sell multiple higher tiers and neither offers a performance guarantee — these are software subscriptions, not link services.

The index difference: two different maps of the same web

No backlink tool sees the whole web. Each runs its own crawler, makes its own decisions about what to crawl and how often, and prunes dead links on its own schedule. That's why the same site can show 1,200 referring domains in one tool and 800 in the other — and why neither number is "wrong."

On paper, Semrush claims the larger raw index: more than 43 trillion backlinks from 390 million referring domains, refreshed at least hourly according to its Backlink Analytics page. Ahrefs publishes 35 trillion external backlinks (including historical records), 493 billion pages in its live index, and 210 million domains, with fresh backlink data flowing in every 15 minutes.

Raw size is a headline number, though, not a verdict. A bigger index can mean broader discovery, or it can mean more dead and duplicate links retained. What matters for link vetting is consistency: pick one index and compare every prospect inside it, so a site with 400 referring domains and a site with 4,000 are being measured with the same ruler. Mixing indexes mid-analysis is how misleading metrics creep into buying decisions.

DR vs Authority Score: what each metric actually counts

This is the core difference between the two tools, and it's a philosophical one.

Ahrefs Domain Rating (DR) is a pure link-graph metric. Per Ahrefs' own documentation, DR measures the strength of a site's backlink profile relative to every other site in the Ahrefs index, on a 0–100 scale. Linking domains pass rating in proportion to their own DR, and each domain splits the rating it passes equally among the sites it links to — so a link from a modest site with few outbound links can move DR more than a link from a huge site that links out to thousands of domains. Crucially, Ahrefs states that DR ignores organic traffic, spam signals, and content quality. That's not an oversight; it's the design. DR answers one question — how strong is this link profile on paper? — and nothing else.

Semrush Authority Score (AS) is a compound metric on a 1–100 scale built from three factor groups: Link Power (the quality and quantity of dofollow backlinks), estimated organic traffic, and a set of natural-profile checks. Semrush publicly lists six spam signals it evaluates, including a site having no rankings in Google's top 100, more than 90% dofollow referring domains, a mismatch between link-profile size and organic traffic, referring domains clustered on the same IP address or network, and the presence of another domain with an identical backlink profile.

The practical consequence: DR tells you what the links look like; AS tells you whether the whole picture looks natural. A site propped up by a link network can carry a respectable DR while its AS lags, because AS notices the missing traffic and the clustered IPs. Conversely, a legitimate niche site with a small but clean profile can score better on AS relative to its DR. Neither metric reads the actual content of the page — a limitation both share with every third-party score, which is why fake domain rating schemes work on buyers who look at one number and stop.

When Ahrefs and Semrush disagree, which do you trust?

Neither — at least not the scores by themselves. Disagreement between DR and AS isn't noise to be averaged away; it's information. Here's the working logic we'd suggest:

High DR, low AS: treat as a red flag. The link profile is strong on paper, but Semrush's traffic and spam inputs aren't corroborating it. Check the site's estimated organic traffic in either tool. A "DR 70" site with a few hundred monthly visits is the classic signature of an inflated or expired-domain rebuild, and it's the single most common trap in paid placements.

High AS, moderate DR: usually the safer profile. The site earns traffic and passes Semrush's natural-profile checks even if its raw link graph is unremarkable. For a link that's meant to be an editorial vote from a real site, this pattern is generally what you want to see.

Both high: verify the traffic anyway. Two scores from two vendors is corroboration, not proof. Both metrics can be lifted by sustained link building, and neither evaluates the page your link would sit on.

Both low: the answer is probably no — unless the site is genuinely new and growing, which the raw data will show.

The tie-breaker is always the raw data, not the score. Open the referring-domains report in whichever tool you have. Are the linking sites real, topically related, and diverse? Do anchors look editorial or money-keyword stuffed? Is the site's organic traffic trending up, flat, or cratering after a core update? Ten minutes in the underlying reports beats any amount of score arithmetic — the full checklist is in how to check backlink quality.

One more practical point: DR is the industry's quoting convention. Guest post marketplaces, outreach sellers, and most agencies price and describe inventory in DR terms. That makes Ahrefs the tool you'll use to verify sellers' claims against the same index they're quoting from — and it makes AS valuable as an independent second opinion, precisely because it's calculated differently and is harder to inflate with links alone.

Ahrefs for backlink analysis

Ahrefs built its reputation on its link index, and its backlink tooling reflects that focus. Site Explorer reports followed vs nofollowed links, anchor text distributions, broken inbound and outbound links, and — importantly for vetting — estimated organic traffic for both linking pages and linking domains, so you can see whether a prospective linking site has a real audience. The index is refreshed with new backlink data every 15 minutes per Ahrefs' published figures, and filters let you slice links by type, platform, and domain rating. Pricing starts at $129/month for the Lite plan at the time of writing, with a $29/month Starter tier and a limited free tier for basic checks. The trade-off is scope: you're paying primarily for depth in the link graph, and DR by design won't warn you about spam or traffic problems — you have to open the traffic reports yourself.

Semrush for backlink analysis

Semrush's Backlink Analytics sits inside a broader all-in-one suite, and its published index is the largest headline number in the industry: 43+ trillion backlinks across 390 million referring domains, refreshed at least hourly. Reports cover dofollow/nofollow attribution, newly discovered and lost links, anchor text, source-page details, and side-by-side competitor comparisons. Its distinctive contribution to link vetting is Authority Score's compound design — because AS bakes in estimated traffic and six documented spam checks, a weak AS is an early warning that a pure link metric would miss. Entry pricing is $139/month month-to-month at the time of writing (lower on annual billing), with a limited free tier. The trade-off runs the other way from Ahrefs: a compound score is harder to diagnose — when AS is low, you still need the underlying reports to learn which input dragged it down.

The honest answer: most serious link buyers reference both

If you buy or audit links regularly, the two tools are complements, not substitutes. Ahrefs gives you the industry-standard ruler (DR) and fast index updates for verifying sellers' claims; Semrush gives you an independently calculated second opinion that penalizes exactly the manipulation patterns paid-link sellers use. If budget forces a choice for backlink work specifically, the deciding question is what you'll do most: verify DR-quoted inventory and dig into link profiles (Ahrefs), or monitor your own profile's health inside a broader SEO workflow (Semrush). Free tiers on both, plus the wider field of backlink checkers, can cover occasional spot checks.

FAQ

Why do Ahrefs and Semrush show different backlink counts for the same site? Because they run separate crawlers over different slices of the web on different schedules, and they prune dead links differently. Counts for the same domain routinely differ between tools, and update timing (every 15 minutes for Ahrefs' backlink data, at least hourly for Semrush's database, per each vendor) means even overlapping links can appear at different times. Neither count is the "true" number — Google's index is different from both.

Is a DR 50 the same as an Authority Score 50? No. DR is a link-only metric relative to the Ahrefs index; AS is a compound of link power, estimated organic traffic, and spam signals. The two aren't convertible, and comparing a DR value to an AS value is a category error. Compare DR to DR and AS to AS, always within one tool's index.

Which tool is better for spotting manipulated or spammy sites? Authority Score is the more suspicious metric by design — Semrush documents six spam checks, including dofollow ratios over 90%, link-vs-traffic mismatches, and referring domains clustered on shared IPs. But DR users can reach the same conclusion manually by checking a site's organic traffic and referring-domain quality in Ahrefs. The signal is available in both tools; Semrush surfaces it in the score, Ahrefs leaves it in the reports.

Do I need both tools just to vet backlinks? Not necessarily. One tool used consistently — score plus traffic plus referring-domain review — catches most bad placements. A second index is most valuable when money is on the line and the numbers look too good: cross-referencing DR against AS (or either against real traffic) is the fastest way to expose an inflated site before you pay for it.

Can sellers inflate DR or Authority Score? DR can be inflated with high-DR links from domains with few outbound links, which is why "high DR, no traffic" sites are so common in cheap link marketplaces — we break down the mechanics in our fake domain rating guide. Semrush states AS is harder to game because it requires corroborating organic traffic and a natural link profile, but no third-party score is tamper-proof. Verify the raw data before you buy.

Vet the link, not just the score

Ahrefs and Semrush will tell you what a site's link profile looks like — but neither tells you whether the placement you're about to pay for will be a real, indexed, traffic-bearing link six months from now. That's the part we do differently at LinkVetted: every placement is on a traffic-verified site, you see the live URL and approve it before payment, and links are covered by a 6-month replacement guarantee, from $69 per link. If you'd rather spend your time on strategy than on cross-referencing two indexes, see our pricing or explore our link building services — and if you're still comparing options, what backlinks should cost is a fair place to start.