Published 2025-01-15 · Seotific Team
📅 12 April 2025 · ⏱ 8 min read
If you have run keyword research in Semrush, Ahrefs, and Google Keyword Planner simultaneously, you've seen the disagreement firsthand. The same keyword returns wildly different volume estimates — sometimes by a factor of ten. One tool shows 8,100 monthly searches. Another shows 720. A third shows 2,400. Which one is right?
The honest answer: probably none of them, exactly. But understanding why they disagree tells you how to use each one correctly.
Most SEO tools don't have direct access to Google's data. Google doesn't publish search volume, click data, or ranking positions to third parties. Everything you see in third-party tools is modelled, estimated, or sampled — and the models vary significantly between providers.
Semrush and Ahrefs primarily use clickstream data — samples from browser extensions, ISPs, and other sources — extrapolated to estimate total search volume. The sample size, geographic coverage, data freshness, and extrapolation model all affect the final number significantly.
Google Keyword Planner uses actual Google search data but rounds aggressively to ranges (100–1K, 1K–10K) and is optimised for advertisers, not SEO. It also inflates volume for navigational and branded queries.
The practical implication: treat volume numbers as directional signals, not absolutes. A keyword showing 8,100 in Semrush and 2,400 in Ahrefs is clearly higher-volume than one showing 90 and 70. The relative position matters more than the precise number.
Ranking positions are not a single number — they vary by location, device, search history, and time of day. A page ranking position 4 in London may rank position 11 in Manchester. Most tools report rankings from a small set of data centre locations at a fixed point in time. This gives you a useful approximation, but comparing your position across three different tools will show three different numbers for the same keyword on the same day.
Google Search Console is the most accurate source of ranking data because it uses Google's actual server logs. But it averages over the selected date range and only covers keywords where your site already has impressions. It doesn't tell you where you rank for keywords you don't yet appear for.
Ahrefs, Semrush, and Moz each crawl the web independently to discover backlinks, on different schedules. A link discovered by Ahrefs in January may not appear in Semrush's database until March. Use one tool consistently for backlink analysis rather than comparing across tools — the absolute numbers matter less than the trend within the same tool over time.
Run a technical audit on the same URL in Screaming Frog, Semrush, and a custom crawler and you will get three different issue counts. This isn't because one is correct and others are wrong — it's because they're measuring different things from different vantage points.
Some tools fetch pages as simple HTTP requests — they see the HTML source but not JavaScript-rendered content. Others use a headless browser to render pages as Google would. If your site loads content via JavaScript, a simple HTTP crawler will report missing H1 tags and empty meta descriptions — because those elements are injected by JavaScript, not present in the raw HTML.
This is why the same tool can return contradictory results depending on configuration. Seotific's audit engine uses Playwright to render pages exactly as a browser would, so what it measures matches what Google sees.
Word count and keyword density figures differ across tools because some count all text on the page — including navigation, footer, and sidebar — while others strip these and count only the main content zone. A page with 800 words of real content might show 1,400 words in a tool that counts navigation text. The content-zone figure is what matters for SEO purposes.
Different tools apply different thresholds for the same check. One tool flags meta descriptions over 155 characters as "too long." Another uses 160. A third uses 158. All are approximations of Google's typical truncation point, which itself varies based on SERP format and device. None is definitively correct.
Third-party traffic estimates are the least reliable data type in SEO. Tools like Similarweb, Semrush Traffic Analytics, and Ahrefs Site Explorer provide modelled figures based on clickstream data, keyword rankings, and estimated click-through rates.
For large, high-traffic sites these can be reasonably accurate in aggregate. For small and medium sites (under 100,000 monthly visits), they can be wrong by 50–80%. This matters enormously for competitive research — if you're benchmarking your 15,000 monthly visits against a competitor's "estimated 120,000 visits," that competitor number may be anywhere from 40,000 to 300,000.
The only accurate traffic data for any domain is in that domain's own Google Analytics or Search Console. Everything else is an approximation.
None of this makes SEO tools useless — they're indispensable. It means understanding what each tool measures well and where it's approximating.
Use Google Search Console for the most accurate data on your own site's rankings, clicks, impressions, and indexation. It's the only tool with direct access to Google's data for your domain. Use third-party tools for competitive research, keyword discovery, and link analysis — knowing you're working with modelled data, not ground truth.
The most effective practitioners triangulate: they compare signals across sources, weight more heavily the data closest to the source (GSC for your own site, actual SERP checks for ranking positions), and make decisions based on patterns rather than precise numbers. A keyword that shows declining trend in Google Trends, falling impressions in GSC, and reduced estimated volume in Ahrefs is probably genuinely declining — even if you can't say exactly by how much.
Seotific draws a clear line between what's factually measurable and what's estimated. Factually measurable: whether a canonical tag is present and what it says, whether an H1 exists and its exact text, whether a redirect chain exists and how many hops it takes, whether an image has an alt attribute. These are binary checks — either present or not.
Estimates — keyword density percentages, content quality scores, competitor traffic figures — are reported with their reasoning. "Meta description is 48 characters, below the recommended 150–160 range for CTR optimisation" rather than simply "error." Context converts data into decisions. That's the difference between a tool that generates reports and one that drives action.
Seotific puts all of this analysis into action — from 60+ check page audits to AI-powered strategy recommendations, all in one tool.
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