How close is Ahrefs organic traffic to reality?

I quote Ahrefs organic traffic numbers in pitches and audits. However, I know this traffic is modeled, so I was curious to see how close it was to data reported in GA4. I pulled Ahrefs' estimated organic traffic for 19 client sites and compared it against what GA4 recorded for the same month.

Methodology

I pulled Ahrefs estimated organic traffic for July 2026, subdomains mode, all countries. Then I pulled GA4 sessions for the same window and filtered to google / organic. Ahrefs only models Google. GA4's Organic Search channel folds in Bing, Yahoo, DuckDuckGo and a long tail of others. The GA4 filter keeps the comparison even.

Data from all 19 sites are listed below, anonymized for client privacy.

Results

A difference ratio of 1.00x means Ahrefs matched GA4. Above 1.00x means it estimated high, below means it estimated lower. The results range from 0.16x to 2.51x.

Analysis

• Median difference ratio: 0.99x
• Mean absolute error: 54%
• Sites with Ahrefs within 25% of GA4: 5 of 19

At first glance the 0.99x median difference makes Ahrefs look close to perfect. However, this is really just major differences on each end of the spectrum. Nine sites came in higher than GA4, and ten were lower.

Website 1 was estimated at 192 visits and got 1,234, so Ahrefs modeled about a sixth of the measured GA4 traffic. Website 19 was estimated at 8,531 and got 3,402, so Ahrefs more than doubled it. The "error" scatters in both directions.

The wide ranges of difference ratios make Ahrefs difficult to extrapolate from. For example, if Ahrefs ran 30% high on every site, you could multiply by 0.7 and move on with a "real" GA4 number, but with no clear pattern there is nothing to correct with.

GA4 is not perfect either

GA4 likely undercounts traffic in most scenarios. Ad blockers, cookie consent banners and privacy settings like Safari's tracking prevention can all block real user sessions from being tracked.

Every GA4 figure in the table is probably lower than reality, which means the sites where Ahrefs estimated low are worse than they look, and the sites where it estimated high are better than they look. It does not change the overall finding, but it does add context that both tools are working with limited data.

Ahrefs still has valuable data

This finding is only based on comparing one month of data, a larger comparison may show Ahrefs is more accurate to GA4 in the aggregate. Regardless, Ahrefs is still a valuable tool despite the discrepancy.

Ahrefs is still a strong source for directional trends on website traffic. The modeling methodology is consistent month over month, so if a site slides for four straight months in Ahrefs, something real is happening even when the absolute number is different from GA4.

It also works for competitor research, because nothing else can see a site whose analytics you do not own. We should just read the output as a range rather than a real figure. If Ahrefs says a competitor gets 10,000 organic visits, what you know is that they get somewhere in the thousands.

It does not work for client reporting when we have access to GA4 or Search Console with first party data. However, Ahrefs never sold itself as a measurement tool. It models traffic from keyword volume and estimated click-through rates. SEOs and digital marketers can continue to use it as a guide rather than an absolute source of truth.