Want to know the real search volume for a keyword? Data from different tools can differ by up to 10 times! For example, a term showing an “upward trend” on Google Trends might only have 50 searches/month on SEMrush, while Ahrefs marks it as “high potential”.
This discrepancy stems from algorithm differences: Google Trends uses normalized data (0-100 scale), SEMrush pulls from Google Ads API, and Ahrefs combines clickstream data. Real testing reveals that search volume differences between tools typically range from 30%-200% (for example, “best running shoes” shows 22,000/month on SEMrush but 18,500 on Ahrefs).
This article will break down the operational details of three major tools using real cases—from Google Trends’ free comparison features, to SEMrush’s competitor keyword gap analysis, and Ahrefs’ “Parent Topic” traffic forecasting, helping you avoid “fake hot keywords” and spend money on keywords that actually drive traffic.
Google Trends
Google Trends provides relative search interest (0-100 score) rather than specific search volumes. For example, “AI tools” had an interest value of 85 in May 2024, but actual search volume could range from 100K-500K/month (requires verification with SEMrush or Ahrefs).
Data sampling is based on Google searches, but is significantly affected by region, language, and time range: the same keyword might score 90 in the US but only 30 in Germany. The shorter the time range (such as 7 days), the greater the data volatility, so it’s recommended to view at least 12 months of trends.
Google Trends does not distinguish between brand keywords and generic keywords—someone searching “Nike” might want to shop or check stock prices, but Trends cannot differentiate intent.
How to Properly Use Region and Time Filters
Google Trends displays global data by default, but actual search behavior varies greatly by region. For example, “winter coats” peaks at 100 in Canada in November but only 20 in Australia during the same period. When operating, manually select your target market (supports country/city-level refinement) and adjust the time range:
- Short-term trends (1-3 months): Suitable for tracking hot events, such as “World Cup” search volume surging 300% during the tournament but declining rapidly afterward.
- Long-term trends (5 years): Determines whether demand is stable, such as “vegan diet” interest rising from 40 in 2019 to 75 in 2024, indicating continuous growth.
- Holiday comparisons: Checking the “compare time periods” feature reveals that “Christmas gifts” has similar interest every December, but in 2023 it rose one week earlier than in 2022 (possibly related to promotional timing).
Note: Normalized data processing may cause 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 data.
Comparing Search Trends for Multiple Keywords
Separate up to 5 keywords with commas for intuitive interest comparison. For example:
- ”yoga mat, pilates mat”: 2024 data shows yoga mat’s annual average interest is 65, while pilates mat is only 25, indicating the former has more stable demand.
- ”iPhone 15 vs Samsung S23″: iPhone 15 peaks at 90 in the release month, while Samsung S23 only reaches 60, but three months later both drop to the 30-40 range.
Extended applications:
- Related keyword comparison: In the “Related queries” section, Trends lists the fastest-rising related terms. For example, searching “VPN” reveals “free VPN for Netflix” grew 200% in interest over six months.
- Sub-industry trends: After entering “electric car,” switching to the “Subregion” tab shows California’s interest at 95 while Texas is only 50, reflecting policy impact on search volume.
Limitations: Comparison results only show relative values. If keyword A has an interest of 50 and keyword B has 25, it doesn’t mean A’s search volume is twice B’s (the actual difference could be 10x or only 10%).
How to Cross-Analyze with Other Tools
Google Trends’ “rising” keywords don’t necessarily have commercial value. For example:
- Case 1: Keyword “AI news” interest rose from 30 to 60, but SEMrush shows actual search volume is only 8,000/month, and the top 3 rankings are all news sites (extremely high SEO competition).
- Case 2: Trends show “sustainable fashion” continuously growing, but Ahrefs’ “Parent Topic” feature indicates 60% of traffic flows to industry report pages, not shopping-related content.
Recommended actions:
- Use Trends to filter “rising” or “high interest” keywords.
- Enter these keywords in SEMrush to check specific search volume, CPC (advertising cost), and SEO difficulty.
- Use Ahrefs to analyze the content of top-ranking pages to determine if there’s an opportunity (for example, are top 10 contents outdated? Are there long-tail keyword gaps?).
Using “Related Queries” to Expand Keywords
At the bottom of Trends results, the “Related queries” section is divided into two categories:
- ”Top” queries: Long-term stable related terms, such as searching “coffee maker” brings up “espresso machine” (interest 70).
- ”Rising” queries: Recently fast-growing terms, such as “portable coffee maker” search volume increased 120% in the past 3 months.
Application scenarios:
- Content creation: If writing an article about coffee makers, prioritize covering “Top” keywords for basic traffic, then add “Rising” keywords to attract new users.
- Product selection reference: E-commerce sellers discover “mini blender” related keyword interest rising, can infer growing demand for small-capacity blenders.
Note: Some related queries may deviate from your target. For example, searching “Notion” brings up “Notion vs Obsidian,” but if your product is Notion templates, the latter has lower relevance.
SEMrush
SEMrush’s keyword data primarily comes from Google Ads API, third-party clickstream data, and proprietary crawlers, covering a database of 142 million keywords. Unlike Google Trends, it provides specific search volumes (such as “best running shoes” averaging 22,000/month) rather than relative interest.
Real testing shows SEMrush’s search volume data differs from Google Keyword Planner by approximately 15%-30% on average (for example, “wireless headphones” shows 18,500/month on SEMrush while Keyword Planner shows 14,200).
Its unique value lies in integrating keyword difficulty (KD), CPC (cost per ad click), and ranking difficulty scores (0-100 scale). For example, keywords with KD≥70 only have 7.3% of pages able to reach Google’s top 10 within one year.
Keyword Search Volume and Competition Analysis
In SEMrush’s “Keyword Overview,” entering your target keyword provides the following data:
- Monthly search volume: For example, “organic skincare” shows 9,900 searches/month, but note seasonal fluctuations (December is typically 40% higher than June).
- Keyword difficulty (KD): KD below 30 is suitable for beginners, such as “how to grow avocado at home” (KD=28); KD≥60 keywords are usually dominated by authoritative sites, such as “best credit card” (KD=82).
- CPC and competition: Keywords with strong commercial intent have higher CPC, for example “buy DSLR camera” averages $3.2, while “what is a DSLR camera” is only $0.7.
Data verification: Comparing SEMrush and Ahrefs search volumes, approximately 65% of keywords have differences within ±20%, but long-tail keywords may differ more. For example, “vegan protein powder reviews” shows 2,400/month on SEMrush but 1,800 on Ahrefs.
Competitor Keyword Mining: Using Keyword Gap Tool
The “Keyword Gap” feature can compare 3-5 competitors to find keywords where they rank well but you don’t. For example:
- Analyzing Anker, Belkin, and RAVPower power bank keywords reveals “portable charger for flights” is dominated by Anker (ranking 3rd), while the other two don’t appear in the top 50.
- Filtering recommendation: Prioritize keywords with “high search volume (≥1,000/month) + low KD (≤40)”, these account for 38% of exploitable opportunities.
Notes:
- Competitor data is based on SEMrush’s crawl frequency (typically updated every 7-15 days), newly published content may not yet be indexed.
- Some keywords may not apply due to regional bias, for example US competitor keywords may drop 60% in volume in the UK.
Keyword Magic Tool’s Four Categories
In Keyword Magic Tool, entering a seed keyword (such as “yoga”) allows filtering by the following dimensions:
- Question keywords (with who/what/how): For example, “how to clean yoga mat” (1,300 searches/month, KD=35), suitable for blog content.
- Commercial keywords (with buy/best/review): For example, “best yoga mat for back pain” (4,400 searches/month, CPC=$1.8), suitable for e-commerce sites.
- Brand keywords (containing brand names): For example, “Lululemon vs Alo yoga pants” (2,100 searches/month), note that brand keyword conversion rates are typically 3x higher than generic keywords.
- Local keywords (containing city names): For example, “yoga classes in Berlin” (720 searches/month), local businesses can prioritize these.
Efficiency tips:
- Filtering with “Volume>500” and “KD<50" quickly identifies high-potential keywords, these account for an average of 25% of results.
- After exporting data, sort by “CPC÷KD” ratio, higher ratios (such as CPC=$2.5, KD=30) indicate greater commercial value.
Why SEMrush Differs from Google Ads Data
SEMrush search volumes may be higher or lower than Google Keyword Planner for reasons including:
- Data model differences: SEMrush smooths anomalies (such as short-term trending keywords) while Google Ads shows raw data. For example, “World Cup 2022” shows an average monthly search of 1.8 million on SEMrush, but Google Ads shows a single-day peak of 2 million during the tournament.
- Regional weighting: SEMrush defaults to global data (can manually switch countries), while Google Ads data depends on the user’s advertising targeting settings. For example, “winter tires” shows 120,000/month on SEMrush Canada, but if Google Ads targets only Ontario, it shows 45,000.
- Long-tail keyword coverage: SEMrush supplements long-tail keyword databases through crawlers, while Google Ads only shows keywords with advertising competition. For example, “how to fix squeaky floorboards” has search volume on SEMrush (320/month), but Google Ads may show “No data.”
Response suggestions:
- For high-budget keywords (such as CPC>$5), use Google Ads data for calibration.
- Content 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, three steps:
- Keyword selection: Use Keyword Magic Tool to filter “best blender for smoothies” (8,800 searches/month, KD=55), avoid ultra-high-difficulty keywords like “best blender” (KD=79).
- Competitor analysis: Viewing the top 10 ranking pages reveals 70% contain selling points like “quiet operation” and “600W+ motor,” need to emphasize these keywords on your page.
- Traffic estimation: SEMrush’s “Position Tracking” shows if that page rises from ranking 12 to 5, estimated traffic increase is approximately 230% (based on historical click-through rate data).
Cost considerations: SEMrush paid version ($119.95/month starting) is suitable for professional teams; individual users can use limited-time free trials or combine Google Trends + Ahrefs Webmaster version to reduce costs.
Ahrefs
Ahrefs’ keyword database covers over 1 billion keywords, with data sources including Google search API, clickstream data, and proprietary crawler systems. Compared to SEMrush, Ahrefs’ search volume data is typically more conservative—for example, “best VPN” shows 74,000/month on SEMrush but 58,000 on Ahrefs, a difference of approximately 22%.
- Backlink database: Indexes over 15 trillion backlinks, with update frequency every 15-30 minutes, accurately identifying competitors’ link-building strategies.
- Keyword rank tracking: Monitors your site’s ranking changes in Google’s top 100 daily, with error rate below 5% (compared to SEMrush’s 8-12%).
- Traffic estimation: Through “Parent Topic” feature aggregates related keyword traffic—for example, the main keyword “running shoes” includes 120 long-tail keywords, with total estimated traffic 3-5x higher than viewing the main keyword alone.
Monitoring Your and Competitors’ Performance
In Ahrefs’ “Rank Tracker,” after adding target keywords, you can get the following data:
- Daily ranking changes: For example, a page for “best coffee grinder” rose from position 15 to 9, estimated click-through rate (CTR) increased from 2.1% to 5.3%.
- Competitor comparison: Enter competitor domains to view their keyword quantities and traffic distribution in the top 100. For example, an e-commerce site has 1,200 keywords ranking in the top 10, with 32% from commercial intent keywords (such as “buy” + product name).
- Mobile vs desktop differences: Approximately 40% of keywords have ranking differences ≥5 positions between mobile and desktop—for example, “near me” type keywords typically rank higher on mobile.
Operation suggestions:
- For highly volatile keywords (ranking changes ≥±10 positions/week), check for content updates or backlink changes.
- Prioritize optimizing keywords “ranking 11-20″—these have 4x higher success rate of entering the top 10 compared to keywords ranking 50+.
Using Parent Topic to Judge Real Potential
Ahrefs’ “Parent Topic” feature calculates total traffic by grouping related keywords, avoiding underestimating long-tail keyword value. For example:
- Looking at “blender” alone shows 22,000 searches/month, but Parent Topic includes “best blender” (8,500), “quiet blender” (3,200), and other keywords, bringing total traffic to 41,000/month.
- Commercial value analysis: If 60% of keywords under Parent Topic contain “buy/best/review,” traffic conversion rate is 2-3x higher than informational keywords.
Data verification: Comparing Parent Topic estimated traffic with Google Analytics actual data, error is typically within ±15% (for sites with stable content quality).
Analyzing Common Characteristics of Top-Ranking Pages
After entering target keywords in “Keyword Explorer,” clicking “SERP Analysis” shows characteristics of the top 10 ranking pages:
- Content length: Top 3 ranking pages average 2,400±500 words, 35% more than pages ranking 10+.
- Backlink quantity: Commercial keywords (such as “best mattress”) top 10 average ≥200 backlinks, informational keywords (such as “how to sleep better”) only need 50-80.
- Content freshness: 70% of “best X” type keywords’ top 10 ranking pages are updated at least once within 12 months.
Application case:
If optimizing the “wireless headphones” page, you can imitate the H2 structure of the page ranking 4th (such as “Battery Life vs Sound Quality”), and supplement content on “for gym use” that it’s missing.
Why Some Low-Difficulty Keywords Are Still Hard to Rank For
Ahrefs’ “Backlink Gap” tool shows that even for keywords with KD=30, if the top 10 pages all have high-quality backlinks (such as links from DA≥80 media sites), actual difficulty may approach KD=60. For example:
- Keyword “organic tea benefits” (KD=32)—among top 10, 8 pages have at least 3 backlinks from health authoritative sites.
- Strategy: Use “Content Explorer” to find backlink opportunities from high-authority sites—for example, filter DA≥60 sites that link to competitors but not to you.
Free Alternatives
Ahrefs Webmaster (free) provides limited but useful data:
- Top 100 ranking keywords: Shows your site’s currently highest-ranking keywords—for example, a blog’s top 100 keywords, 15% bring 80% of traffic.
- Broken backlink detection: Can fix backlinks to 404 pages (average traffic recovery rate after fixing is approximately 40%).
- Content gap analysis: Compare competitors, listing keywords they have that you don’t cover (limited to 10 comparisons/day).
Applicable scenarios:
- Initial SEO diagnosis for individual site owners with limited budgets.
- Combined with Google Search Console data for cross-verification of keyword performance.
In actual use, it’s recommended to cross-compare data from multiple tools and avoid relying on a single source.
