How to find the true search popularity of a keyword? The data from different tools can vary by as much as 10x! For example, a word that shows an “upward trend” on Google Trends might have only 50 searches/month on SEMrush, while Ahrefs marks it as “high potential“.
Behind this is a difference in algorithms: Google Trends uses normalized data (0-100 score), SEMrush pulls from the Google Ads API, and Ahrefs uses clickstream data. In real-world tests, search volume differences between tools commonly range from 30% to 200% (for example, “best running shoes” shows 22,000/month on SEMrush and 18,500 on Ahrefs).
This article will use real-world cases to break down the operational details of the three major tools—from Google Trends’ free comparison feature to SEMrush’s competitor keyword gap analysis and Ahrefs’ “Parent Topic” traffic forecasting—to help you avoid “fake hot keywords” and spend your money on keywords that truly bring traffic.
Google Trends
Google Trends provides relative search popularity (0-100 score), not specific search volume. For example, “AI tools” had a popularity score of 85 in May 2024, but the actual search volume could be between 100,000 and 500,000/month (this needs to be verified with SEMrush or Ahrefs).
The data is based on Google searches but is heavily influenced by region, language, and time range: the same keyword might have a popularity of 90 in the U.S. but only 30 in Germany. The shorter the time range (e.g., 7 days), the greater the data fluctuation; it’s recommended to view at least a 12-month trend.
Google Trends does not distinguish between brand and generic terms—for example, someone searching for “Nike” might want to shop or check stock prices, but Trends cannot segment this intent.
How to use region and time filters correctly
Google Trends defaults to showing global data, but actual search behavior varies greatly by region. For example, “winter coats” can peak at 100 in Canada in November, while only reaching 20 in Australia during the same period. You need to manually select your target market (supports country/city-level granularity) and adjust the time range:
- Short-term trend (1-3 months): Suitable for tracking hot topics, such as the 300% surge in searches for “World Cup” during the tournament, which quickly falls after the event.
- Long-term trend (5 years): To determine if demand is stable, such as “vegan diet” popularity rising from 40 in 2019 to 75 in 2024, indicating continuous growth.
- Holiday comparison: By checking the “Compare” feature, you can see that “Christmas gifts” has similar popularity each December, but in 2023 it started to rise a week earlier than in 2022 (possibly related to promotion schedules).
Note: The data normalization process can lead to misunderstandings. If a keyword has insufficient samples in a specific region, Trends will show “insufficient data” or zero, requiring you to use tools like SEMrush for supplementary information.
Comparing search trends for multiple keywords
You can compare up to 5 keywords by separating them with commas. For example:
- ”yoga mat, pilates mat”: 2024 data shows “yoga mat” had an average annual popularity of 65, while “pilates mat” was only 25, indicating more stable demand for the former.
- ”iPhone 15 vs Samsung S23″: During the launch month, iPhone 15’s popularity peaked at 90, while Samsung S23’s was only 60, but three months later both fell back to the 30-40 range.
Extended applications:
- Related term comparison: In the “Related queries” section, Trends lists the fastest-rising related terms. For example, searching “VPN” might show that “free VPN for Netflix” has grown 200% in popularity over six months.
- Niche industry trends: After typing “electric car,” switching to the “Subregion” tab shows that California has a popularity of 95, while Texas is only 50, reflecting the impact of policy on search volume.
Limitations: The comparison results only show relative values. If keyword A has a popularity of 50 and B has 25, it does not mean A’s search volume is twice that of B (the actual difference could be 10x or only 10%).
How to combine with other tools for cross-analysis
An “upward trend” word on Google Trends does not necessarily have commercial value. For example:
- Case 1: The keyword “AI news” rose in popularity from 30 to 60, but SEMrush showed its actual search volume was only 8,000/month, and the top three ranking sites were all news outlets (with extremely high SEO competition).
- Case 2: The trend shows “sustainable fashion” is continuously growing, but Ahrefs’ “Parent Topic” feature points out that 60% of the traffic for this term goes to industry report pages, not shopping-related content.
Recommended actions:
- Use Trends to filter for “rising” or “high-popularity” words.
- Input these words into SEMrush to see specific search volume, CPC (cost per click), and SEO difficulty.
- Use Ahrefs to analyze the content of the top-ranking pages and determine if there’s an opportunity (e.g., is the content of the top 10 outdated? Are there any long-tail keyword gaps?).
Using “Related queries” to expand keywords
At the bottom of the Trends results page, the “Related queries” section is divided into two categories:
- ”Top” queries: Long-term stable related terms, such as “espresso machine” (popularity 70) appearing after searching “coffee maker.”
- ”Rising” queries: Recently fast-growing terms, such as “portable coffee maker,” which saw a 120% increase in search volume in the last 3 months.
Application scenarios:
- Content creation: If writing an article about coffee makers, prioritize covering “Top” terms to ensure a baseline of traffic, then add “Rising” terms to attract new users.
- Product selection reference: An e-commerce seller who notices the rising popularity of the related term “mini blender” can infer an increase in demand for small-capacity blenders.
Note: Some related terms may be off-topic. For example, searching “Notion” might bring up “Notion vs Obsidian,” but if your product is Notion templates, the latter is less relevant.
SEMrush
SEMrush’s keyword data primarily comes from the Google Ads API, third-party clickstream data, and its own web crawlers, covering a database of 142 million keywords. Unlike Google Trends, it provides specific search volume (e.g., “best running shoes” averages 22,000/month) rather than relative popularity.
Tests show that SEMrush’s search volume data differs from Google Keyword Planner by an average of about 15%-30% (for example, “wireless headphones” shows 18,500/month on SEMrush and 14,200 on Keyword Planner).
Its unique value lies in integrating keyword difficulty (KD), CPC (cost per click), and a ranking difficulty score (0-100). For example, only 7.3% of pages with a KD ≥ 70 can reach the Google top 10 within a year.
Keyword search volume and competition analysis
By entering a target keyword into SEMrush’s “Keyword Overview,” you can directly get the following data:
- Average monthly search volume: For example, “organic skincare” shows 9,900 searches/month, but you need to be aware of seasonal fluctuations (December is usually 40% higher than June).
- Keyword difficulty (KD): A KD value below 30 is suitable for beginners, like “how to grow avocado at home” (KD=28); a KD ≥ 60 is typically dominated by authority sites, like “best credit card” (KD=82).
- CPC and competition: Keywords with strong commercial intent have higher CPC. For example, “buy DSLR camera” has an average CPC of $3.2, while “what is DSLR camera” is only $0.7.
Data verification: Comparing SEMrush and Ahrefs’ search volumes, about 65% of keywords have a difference of within ±20%, but long-tail keywords can vary more. For example, “vegan protein powder reviews” shows 2,400/month on SEMrush and 1,800 on Ahrefs.
Competitor keyword mining: using the Keyword Gap tool
The “Keyword Gap” feature allows you to compare 3-5 competitors and find keywords they rank for but you don’t. For example:
- Analyzing the power bank keywords of Anker, Belkin, and RAVPower reveals that “portable charger for flights” is exclusively owned by Anker (ranking #3), while the other two do not appear in the top 50.
- Suggested filter conditions: prioritize words with “high search volume (≥1,000/month) + low KD (≤40)” for optimization. These words account for 38% of the available opportunities.
Important notes:
- Competitor data is based on SEMrush’s crawling frequency (usually updated every 7-15 days), so newly published content might not be included yet.
- Some keywords may not be relevant due to regional deviations. For example, a competitor keyword for a U.S. site might see a 60% drop in search volume in the U.K.
The four categories of the Keyword Magic Tool
By entering a seed keyword (like “yoga”) into the Keyword Magic Tool, you can filter by the following dimensions:
- Question words (with who/what/how): For example, “how to clean yoga mat” (search volume 1,300/month, KD=35), suitable for blog content.
- Commercial words (with buy/best/review): For example, “best yoga mat for back pain” (search volume 4,400/month, CPC=$1.8), suitable for e-commerce sites.
- Brand words (containing brand names): For example, “Lululemon vs Alo yoga pants” (search volume 2,100/month). Note that brand keyword traffic typically has a 3x higher conversion rate than generic keywords.
- Local words (containing city names): For example, “yoga classes in Berlin” (search volume 720/month). Local businesses can prioritize optimizing these.
Efficiency tips:
- Using filters like “Volume＞500” and “KD＜50” can quickly find high-potential keywords, which on average account for 25% of the results.
- After exporting the data, sort by the “CPC ÷ KD” ratio. Keywords with a higher ratio (e.g., CPC=$2.5, KD=30) have greater commercial value.
Why SEMrush data differs from Google Ads data
SEMrush’s search volume may be higher or lower than Google Keyword Planner, for reasons including:
- Data model differences: SEMrush smooths out anomalies (like short-term trending words), while Google Ads shows raw data. For example, “World Cup 2022” has an average monthly search volume of 1.8 million on SEMrush, but during the event, Google Ads showed a single-day peak of 2 million.
- Regional weighting: SEMrush defaults to showing global data (can be manually switched to a country), while Google Ads data depends on the user’s ad targeting settings. For example, “winter tires” shows 120,000/month on SEMrush for Canada, but if Google Ads targets only Ontario, it might show 45,000.
- Long-tail keyword coverage: SEMrush supplements its long-tail keyword database with crawlers, while Google Ads only shows words with ad competition. For example, “how to fix squeaky floorboards” has a search volume on SEMrush (320/month), but Google Ads might show “no data.”
Suggested actions:
- For high-budget keywords (e.g., CPC＞$5), it’s recommended to calibrate with Google Ads data.
- Content-based websites can prioritize SEMrush’s long-tail keyword data, as it covers more informational queries.
How to use SEMrush to optimize e-commerce product pages
Using “blender” as an example, follow these three steps:
- Keyword selection: Use the Keyword Magic Tool to filter for “best blender for smoothies” (search volume 8,800/month, KD=55), avoiding ultra-high difficulty words like “best blender” (KD=79).
- Competitor analysis: Check the top 10 ranking pages and find that 70% of the content includes selling points like “quiet operation” and “600W+ motor.” These keywords need to be emphasized on your page.
- Traffic estimation: SEMrush’s “Position Tracking” shows that if the page ranks from #12 to #5, the estimated traffic could increase by about 230% (based on historical click-through rate data).
Cost consideration: The paid version of SEMrush (starting at $119.95/month) is suitable for professional teams. Individual users can use a limited-time free trial or combine Google Trends + Ahrefs Webmaster to reduce costs.
Ahrefs
Ahrefs’ keyword database covers over 10 billion keywords, with data sources including the Google search API, clickstream data, and its own crawling system. Compared to SEMrush, Ahrefs’ search volume data is usually more conservative; for example, “best VPN” shows 74,000/month on SEMrush and 58,000 on Ahrefs, a difference of about 22%.
- Backlink database: Indexes over 15 trillion backlinks, with an update frequency of every 15-30 minutes, allowing for precise identification of competitor link-building strategies.
- Keyword ranking tracker: Can monitor a website’s daily ranking changes in the Google top 100, with an error rate below 5% (compared to SEMrush’s 8-12%).
- Traffic estimation: The “Parent Topic” feature aggregates traffic from related keywords. For example, the main keyword “running shoes” includes 120 long-tail keywords, and the total estimated traffic is 3-5x higher than just looking at the main keyword alone.
Monitoring your own and competitors’ performance
In Ahrefs’ “Rank Tracker,” after adding your target keywords, you can get the following data:
- Daily ranking changes: For example, a page on “best coffee grinder” moving from #15 to #9 is estimated to increase its click-through rate (CTR) from 2.1% to 5.3%.
- Competitor comparison: By entering a competitor’s domain, you can view their number of top 100 keywords and traffic distribution. For example, an e-commerce site has 1,200 keywords in the top 10, with 32% of the traffic coming from commercial intent keywords (e.g., “buy” + product name).
- Mobile vs. desktop differences: About 40% of keywords have a ranking difference of ≥5 positions between mobile and desktop; for example, “near me” type keywords usually rank higher on mobile.
Suggested actions:
- For volatile keywords (ranking changes of ≥±10 positions/week), check for content updates or backlink changes.
- Prioritize optimizing keywords that are “ranking 11-20” as they have a 4x higher success rate of entering the top 10 than those below the 50th position.
Using Parent Topic to judge true potential
Ahrefs’ “Parent Topic” feature groups related keywords to calculate total traffic, avoiding underestimating the value of long-tail keywords. For example:
- Looking at “blender” alone gives a search volume of 22,000/month, but the Parent Topic includes “best blender” (8,500), “quiet blender” (3,200), and other words, bringing the total traffic to 41,000/month.
- Commercial value analysis: If 60% of the keywords under a Parent Topic contain “buy/best/review,” the traffic conversion rate is 2-3 times higher than for informational keywords.
Data verification: The error between the Parent Topic estimated traffic and Google Analytics’ actual data is usually within ±15% (for sites with stable content quality).
Analyzing commonalities of top-ranking pages
After entering a target keyword into “Keyword Explorer,” clicking on “SERP Analysis” allows you to view the characteristics of the top 10 pages:
- Content length: The top 3 ranking pages have an average word count of 2,400 ± 500 words, which is 35% more than pages ranking below 10.
- Number of backlinks: The top 10 pages for commercial keywords (e.g., “best mattress”) have an average of ≥200 backlinks, while informational keywords (e.g., “how to sleep better”) only need 50-80.
- Content freshness: 70% of the top 10 pages for “best X” type keywords are updated at least once within 12 months.
Application case:
To optimize a “wireless headphones” page, you can mimic the H2 structure of the page ranking #4 (e.g., “Battery Life vs Sound Quality”) and add content it lacks, such as “for gym use.”
Why some low-difficulty words are still hard to rank for
Ahrefs’ “Backlink Gap” tool shows that even for a keyword with KD=30, if the top 10 pages all have high-quality backlinks (e.g., from media sites with DA≥80), the actual difficulty can be close to KD=60. For example:
- For the keyword “organic tea benefits” (KD=32), 8 of the top 10 pages have at least 3 backlinks from authoritative health-related sites.
- Solution: Use “Content Explorer” to find backlink opportunities from high-authority sites, for example, by filtering for sites with DA≥60 that link to competitors but not to your site.
Free alternatives
Ahrefs Webmaster (free) provides limited but useful data:
- Top 100 keywords: Shows the keywords your site currently ranks highest for. For example, a blog site might find that 15% of its top 100 keywords bring in 80% of the traffic.
- Broken link detection: Allows you to fix backlinks to 404 pages (with an average traffic recovery rate of about 40% after fixing).
- Content gap analysis: Compares with competitors and lists keywords they have but you don’t (limited to 10 comparisons/day).
Suitable scenarios:
- Initial SEO diagnosis for individual webmasters with limited budgets.
- Cross-referencing keyword performance with Google Search Console data.
When in use, it is recommended to cross-reference data from multiple tools to avoid relying on a single source.
