Organic traffic in Ahrefs is calculated based on the keywords that we see your website is ranking for and the search volume of these keywords.
It will be different from the traffic numbers in Google Analytics for a number of reasons:
Ahrefs doesn’t track ALL the keywords that a website is ranking for in organic search results. We track the most popular ones and that is about 120 Million keywords for the US only. In reality, there are billions of keywords, and it’s technically impossible to track all of them.
The exact search volume of keywords. We have an excellent model for calculating monthly search volume of keywords, that combines data from Google Keywords Planner with clickstream data (more details here). This is the best way to calculate search volume of a keyword as of today, and yet even this model is not perfect. This leads to certain discrepancies.
CTR model. Based on the monthly search volume of a keyword and its position in the search results, we estimate how many clicks a target website will get. Only Google knows the real numbers of clicks, so what we have is an estimate, based on studies and research of how people search. That adds yet another layer of a discrepancy.
As such, the data that we show is just an estimate and can’t be treated as the actual search traffic data of a website.
Tip: Marketers use this data to compare websites with one another and see the trends in organic traffic (if the website is growing or losing traffic).
Tip #2: You get the most value from Ahrefs when you look at the actual keywords that your competitor is ranking for and the pages that bring them the most traffic from search. This data is much more accurate than our “big picture“ traffic estimation.