Semrush built its reputation on keyword data. With a database of 26.1 billion keywords spanning 142 geographic databases, it’s one of the largest keyword intelligence platforms in the world — and for SEO professionals, keyword research is typically where they spend the most time in the tool.
But “keyword research” in Semrush isn’t a single feature. It’s a suite of interconnected tools — the Keyword Magic Tool, Keyword Overview, and Keyword Gap — each serving a different part of the research workflow. Understanding how they work together (and where each one falls short) is what separates effective use of Semrush from expensive mediocrity.
This review covers all of it: how each tool works, what the metrics mean, where Semrush outperforms the competition, and where it doesn’t. For a broader look at the full platform, see our Semrush Review 2026.
What Is Semrush’s Keyword Research Tool?
Semrush’s keyword research capability is built across three primary tools:
1. Keyword Magic Tool — The core discovery engine. You enter a seed keyword and Semrush returns thousands of related keywords with full metrics. This is where most keyword research starts.
2. Keyword Overview — The analysis layer. You enter specific keywords (up to 100 at once) and get a detailed breakdown of each: search volume, keyword difficulty, CPC, SERP features, intent, and more. Use this after Keyword Magic Tool to evaluate specific keyword candidates.
3. Keyword Gap — The competitive intelligence tool. You enter your domain and up to four competitors; Semrush shows you exactly which keywords your competitors rank for that you don’t — sorted by opportunity.
These three tools form a complete discovery-to-prioritization workflow. Most guides treat them in isolation; the real power comes from using them in sequence.
Semrush Keyword Magic Tool: How It Works
The Keyword Magic Tool is the most-used feature in Semrush — and for good reason. Enter a single seed keyword and it returns a list of related terms drawn from Semrush’s full database, organized by match type.
The interface: After entering your seed keyword (e.g., “content marketing”), you’re presented with a table of keywords with columns for Volume, KD% (Keyword Difficulty), CPC, Competitive Density, SERP Features, and Intent.
Match type filters:
- Broad Match: All keywords containing all words from your seed, in any order
- Phrase Match: Keywords containing your exact seed phrase
- Exact Match: Keywords that match your seed exactly
- Related: Semantically related terms — not necessarily containing your seed words
The Related filter is underused. It surfaces keywords that your audience searches for around the same topic without including your exact term — critical for building topical authority without keyword stuffing.
Clustering: Keyword Magic Tool groups keywords into topic clusters in the left sidebar. For a seed like “SEO tools,” you might see sub-groups for “free SEO tools,” “SEO audit tools,” “local SEO tools,” and dozens more. This clustering significantly speeds up the process of identifying keyword themes without manually reviewing thousands of rows.
Intent filters: Semrush classifies keywords by intent: Informational (I), Navigational (N), Commercial (C), and Transactional (T). Filtering by intent helps you quickly separate research-stage queries from purchase-ready queries — essential for matching content type to user intent.
Question filter: One click surfaces only question-format keywords (who, what, how, why, when). These are particularly useful for FAQ sections, featured snippet targeting, and “People Also Ask” optimization.
Semrush Keyword Overview: Key Metrics Explained
Once you’ve identified keyword candidates, the Keyword Overview tool is where you evaluate them in detail. Here are the metrics that matter most:
Volume Monthly search volume based on Google data. Semrush’s volume figures are generally reliable for trend direction, though exact numbers may vary from Google Search Console data (which reflects your actual site’s impressions). Treat Volume as a directional indicator, not a precise count.
KD% — Keyword Difficulty Semrush’s proprietary difficulty score, ranging from 0 (easiest) to 100 (hardest). It measures how difficult it would be to rank in the top 10 organic results for a given keyword based on the authority of pages currently ranking.
A few calibration notes:
- 0–29: Low difficulty — achievable for newer domains with good content
- 30–49: Medium — requires solid on-page optimization and some backlinks
- 50–69: Hard — established site + targeted link building needed
- 70+: Very hard — typically dominated by high-authority domains
KD% is a useful first filter but not a final decision signal. Always look at the actual SERP results (which Semrush shows below the KD score) to assess whether the ranking content is truly unbeatable or just ranking on authority without fully serving user intent.
CPC — Cost Per Click The average cost-per-click for this keyword in Google Ads. High CPC = high commercial intent = valuable keyword to rank for organically. A keyword with $8 CPC and only 200 monthly searches may be worth more in organic ROI than a keyword with $0.50 CPC and 5,000 monthly searches.
SERP Features Icons indicating which SERP features appear for this keyword: Featured Snippet, Knowledge Panel, Image Pack, Video Carousel, People Also Ask, Shopping Results, Local Pack, and more. If a keyword has a Featured Snippet, that’s a specific content format to target. If it has a Local Pack, that signals local SEO relevance.
Intent As mentioned above: I/N/C/T. For content strategy, Informational keywords drive blog traffic; Commercial and Transactional keywords drive conversion-stage traffic.
Trend Line A 12-month mini-chart showing search volume trend. Critical for distinguishing genuinely growing keywords from declining ones — and for identifying seasonal keywords where you need to publish content weeks before peak search demand.
Semrush Keyword Gap Tool
The Keyword Gap tool is one of Semrush’s most strategically valuable features — and the most directly actionable for content planning.
How it works: Enter your domain and up to four competitor domains. Semrush cross-references each domain’s ranked keywords and identifies:
- Missing: Keywords your competitors rank for that your site doesn’t rank for at all
- Weak: Keywords where you rank, but lower than competitors
- Strong: Keywords where you outrank competitors
- Untapped: Keywords that multiple competitors rank for, but your site doesn’t appear for in the top 100
The Untapped filter is the strategic goldmine. If three of your four competitors all rank for the same keyword and you don’t appear at all, that’s a clear content gap to close.
Filtering by intent and difficulty: Within the Keyword Gap results, you can apply the same KD% and intent filters as in Keyword Magic Tool. This lets you prioritize gaps that are actually winnable (low-to-medium KD%) and commercially relevant (Commercial/Transactional intent).
Practical output: A well-executed Keyword Gap analysis typically produces 50–200 specific keyword opportunities sorted by priority. This becomes the content roadmap: articles to write, landing pages to create, and existing pages to optimize.
Semrush Keyword Research vs Competitors
How does Semrush’s keyword research stack up against the main alternatives?
| Feature | Semrush | Ahrefs | Moz | Allable |
|---|---|---|---|---|
| Keyword database size | 26.1B keywords | ~20B keywords | ~500M keywords | Billions (via data partners) |
| Keyword Difficulty score | ✅ KD% (0–100) | ✅ KD (0–100) | ✅ KD (0–100) | ✅ Yes |
| Search intent classification | ✅ I/N/C/T | ✅ Yes | ⚠️ Limited | ✅ Yes |
| Keyword Gap / competitor gap | ✅ Built-in | ✅ Built-in | ⚠️ Limited | ✅ Yes |
| Question filter | ✅ Yes | ✅ Yes | ❌ No | ✅ Yes |
| CPC data | ✅ Yes | ✅ Yes | ✅ Yes | ✅ Yes |
| SERP feature detection | ✅ Yes | ✅ Yes | ⚠️ Limited | ✅ Yes |
| Content generation from keywords | ❌ No | ❌ No | ❌ No | ✅ Yes — in same session |
| Chat-first interface | ❌ No | ❌ No | ❌ No | ✅ Yes |
| Entry price | $139.95/mo | $129/mo | $99/mo | Visit allable.ai |
Semrush’s database size advantage over Moz is significant. Ahrefs is the closest competitor in data quality and is often preferred for backlink-centric workflows, while Semrush tends to edge ahead on keyword discovery breadth and the Keyword Gap feature set.
The key differentiator between all three traditional tools and platforms like Allable is what happens after the research. Semrush, Ahrefs, and Moz hand you a spreadsheet of keyword data and leave execution to you. Allable’s chat-first interface lets you go from keyword research to a published content brief — or a fully written article — in the same session, without switching tools.
Limitations of Semrush for Keyword Research
Honest assessment: Semrush is excellent, but not without real limitations.
1. Volume figures are estimates, not absolutes Semrush pulls search volume from multiple data sources and models. Their figures are generally directionally accurate but can deviate significantly from what Google Search Console shows for actual ranking pages. For low-volume keywords (under 500/month), treat Semrush’s volume data as a rough estimate.
2. US-centric by default Semrush’s database quality is strongest for the United States and major English-language markets. Data for smaller international markets can be noticeably thinner. If your primary market is outside the US or UK, verify data quality for your specific location before fully trusting the volume figures.
3. Keyword Difficulty can be misleading KD% is based primarily on the backlink authority of currently-ranking pages. It doesn’t fully account for content quality gaps, SERP intent mismatches (where ranking content doesn’t well serve the query), or zero-click SERP features that suppress click-through rates even for top-ranking pages. A keyword with KD% 65 could still be winnable if the existing content is weak.
4. Requires expertise to interpret correctly The raw data is extensive; the interface is not designed for beginners. Understanding what to prioritize — and what to ignore — in a 50,000-row keyword export requires SEO knowledge that Semrush doesn’t provide. The tool generates data; it doesn’t generate strategy.
5. Limits on free and lower-tier accounts The Pro plan caps results at 10,000 per report. For large keyword research projects spanning multiple competitors and categories, you can hit this ceiling quickly, requiring either Guru-level access or multiple segmented research sessions. See Semrush pricing for a full plan comparison.
Is Semrush the Best Keyword Research Tool?
For seasoned SEO professionals who need the largest possible dataset, the most granular filtering options, and the most comprehensive competitive intelligence — yes, Semrush is arguably the best keyword research tool available.
For beginners, solo content creators, or small business owners who need keyword guidance without becoming data analysts: Semrush is probably overkill. The learning curve is real. The Pro plan alone won’t make you a better keyword researcher; you still need to know how to interpret KD%, when to trust volume figures, how to filter intent, and how to build content strategy from raw data.
This is where AI-first platforms have a genuine advantage. Rather than presenting you with a tool and expecting you to operate it, they interpret the data and surface recommendations in plain language. Allable, for example, handles research through a chat interface — you describe what you’re trying to rank for and your audience, and the platform does the analysis and recommends a content plan. Try Allable’s keyword research tool for businesses that need keyword intelligence without hiring an SEO specialist.
For a full comparison of Semrush vs Allable across all features, including keyword research workflow differences, see our Allable keyword research comparison.
How to Use Semrush for Keyword Research: Quick Tutorial
Here’s the 5-step workflow for getting from zero to a prioritized keyword list in Semrush:
Step 1: Start with Keyword Magic Tool Go to Keyword Research → Keyword Magic Tool. Enter your seed keyword (your core service or product). Set your location (United States for US-focused content). Hit Search.
Step 2: Filter and segment In the results, apply these filters immediately:
- Volume: minimum 100/month (removes noise)
- KD%: set a maximum based on your domain authority (newer sites: max 40; established: max 60)
- Intent: check Informational for blog content, Commercial/Transactional for landing pages
Export the filtered list to a spreadsheet.
Step 3: Review topic clusters Click through the left-sidebar clusters to find thematic sub-groups you may have missed. Export keywords from clusters that align with your content categories.
Step 4: Run Keyword Overview on your shortlist Paste your shortlisted keywords into Keyword Overview (up to 100 at a time). Review the full metrics — especially the trend line and SERP feature data — to finalize your priority list.
Step 5: Run Keyword Gap vs your top 3 competitors Go to Keyword Research → Keyword Gap. Enter your domain and your three main competitors. Filter for “Untapped” keywords with KD% under your threshold. This is your immediate content opportunity list.
That five-step process, done thoroughly, typically takes 2–4 hours and produces a content roadmap that can guide 3–6 months of publishing.
FAQ
Is Semrush good for keyword research? Yes — Semrush is one of the best keyword research tools available for SEO professionals. Its 26.1 billion keyword database, robust filtering, intent classification, and Keyword Gap competitive analysis make it a comprehensive platform. The main caveat is the learning curve and cost — it’s most valuable for experienced SEOs who know how to act on the data.
How accurate is Semrush keyword data? Semrush’s keyword data is directionally reliable, particularly for trends and relative volume comparisons. Exact volume figures can differ from Google Search Console data (which reflects actual search impression data for your specific site). For keywords under 500 monthly searches, treat Semrush volume as an estimate. For volume comparison between keywords — e.g., “is this keyword more popular than that one?” — Semrush is consistently accurate.
How many keywords does Semrush have? Semrush’s database contains 26.1 billion keywords across 142 geographic databases. This is one of the largest keyword datasets available from any commercial SEO tool.
How to do keyword research with Semrush? The core workflow: (1) Enter a seed keyword in Keyword Magic Tool to generate discovery lists; (2) filter by volume, KD%, and intent; (3) export your shortlist; (4) validate in Keyword Overview; (5) find competitor gaps with Keyword Gap tool. See the complete tutorial in the section above.
Is Semrush keyword research free? Partially. The free Semrush account allows approximately 10 keyword searches per day with limited results per query. For serious keyword research, a paid plan starting at $139.95/month is required. Semrush also offers a 7-day free trial (14 days via partner links) that provides full access to the Keyword Magic Tool and all keyword research features.
For Semrush pricing details, see Semrush Pricing 2026. For a full platform comparison, see the Semrush Review 2026 and Allable vs Semrush.