SEO course › Part 2: Keyword research
Keyword metrics are the numbers keyword tools show to help you judge a search term. The four most common are search volume (how often it is searched), keyword difficulty (how hard it may be to rank), cost per click (what advertisers pay) and trend (how interest changes over time). Most of these numbers are estimates, not exact counts.
This lesson explains what each metric means, where the numbers come from, and how to use them together without being misled.
What are keyword metrics and why do they matter?
When you find a list of possible keywords, you need a way to compare them. Keyword metrics give you that comparison.
They help you answer practical questions. Do enough people search this? Can my site realistically rank? Is the traffic commercially valuable? Is interest growing or fading?
You will find these metrics in free and paid tools. See our lessons on free keyword research tools and paid keyword research tools for where to look.
What is search volume?
Search volume is the estimated number of times a keyword is searched in a month, usually for a chosen country. Most tools show an average over the last 12 months.
A few things to keep in mind:
- It is an estimate. Third-party tools model their numbers from different data sources, so two tools often show different volumes for the same keyword.
- It can be a range. Google Keyword Planner often shows ranges (such as “1K–10K”) to advertisers who are not actively spending.
- It is location-specific. “Biryani near me” has very different demand in India than in the UK.
- Similar phrases may be grouped. Tools sometimes combine close variants, such as singular and plural forms.
Treat search volume as a guide to relative demand. A keyword showing 2,000 searches is probably searched more than one showing 200, but the exact figures may be off.
What is keyword difficulty?
Keyword difficulty (often shortened to KD) is a score that estimates how hard it would be to rank on the first page of Google for a keyword. Most tools use a 0 to 100 scale, where higher means harder.
Each tool calculates it differently. Some lean heavily on the number of backlinks (links from other websites) pointing to the pages that already rank. Others mix in other signals. That means a score of 40 in one tool is not the same as 40 in another.
Google does not publish a difficulty score, so KD is always a third-party estimate. Use it to compare keywords inside the same tool, then check the actual results page yourself. Our lesson on SERP analysis shows how.
What does CPC mean for SEO?
CPC stands for cost per click. It is the estimated amount advertisers pay when someone clicks their ad for that keyword in Google Ads. Keyword Planner shows this as a bid range for the top of the page.
You are not paying for organic (unpaid) clicks, so why care? Because CPC is a useful signal of commercial value. If advertisers are willing to pay a lot for a click, that search probably leads to sales.
Keyword Planner also shows a “Competition” column. This measures how many advertisers bid on the keyword. It is about ads, not about how hard it is to rank organically. Learn more about the paid side in our PPC section.
How do you read keyword trends?
The trend shows how interest in a keyword changes over time. Many tools show a small chart of the last 12 months. Google Trends shows interest on a relative scale from 0 to 100, where 100 is the peak for that period and location, not an actual number of searches.
Trends help you spot three patterns:
- Seasonal keywords rise and fall each year, such as “rakhi gifts” before Raksha Bandhan or “Diwali sweets box” in October and November.
- Growing keywords climb steadily, often around a new product or habit.
- Fading keywords decline, which may make them poor long-term targets.
For seasonal topics, publish or update your page a few weeks before the peak so search engines have time to find it.
How do you use keyword metrics together?
No single metric tells the whole story. Here is how they compare:
| Metric | What it tells you | Main limitation |
|---|---|---|
| Search volume | How much demand exists | Estimates vary between tools |
| Keyword difficulty | How strong the competition may be | Each tool uses its own formula |
| CPC | How commercially valuable a click is | Reflects ads, not organic results |
| Trend | Whether interest is rising, falling or seasonal | Google Trends is relative, not absolute |
A worked example
Imagine a home bakery in Hyderabad comparing two keywords:
- “birthday cake”: high volume, high difficulty, moderate CPC, steady trend.
- “eggless photo cake delivery Hyderabad”: low volume, low difficulty, higher relative CPC, steady trend.
The second keyword has far fewer searches. But it is easier to rank for, has clear buying intent, and matches exactly what the bakery sells. For a small business, it is the smarter first target.
A simple routine for each keyword:
- Check the search volume is not zero and that the location is right.
- Check keyword difficulty against other keywords in the same tool.
- Use CPC as a hint of commercial value.
- Look at the trend to time your content.
- Search the keyword yourself to confirm what Google shows.
Remember that metrics ignore business value. A low-volume keyword that brings paying customers can beat a high-volume one that brings casual browsers. Our lesson on keyword prioritization covers this in depth.
Common mistakes to avoid
- Treating search volume from any tool as an exact, guaranteed number.
- Comparing keyword difficulty scores from two different tools.
- Confusing Keyword Planner’s “Competition” column with organic ranking difficulty.
- Skipping keywords that show zero or very low volume without checking; tools can miss new or niche searches.
- Choosing keywords on metrics alone without checking they match what you actually offer.
Key takeaways
- The core keyword metrics are search volume, keyword difficulty, CPC and trend.
- Most keyword metrics are estimates, and different tools show different numbers.
- Keyword difficulty scales are tool-specific; compare scores only within one tool.
- CPC signals commercial value even if you never run ads.
- Trends reveal seasonality, so you can publish before demand peaks.
Frequently asked questions
Which keyword metric matters most?
None matters most on its own. Relevance to your business comes first, then a balance of search volume, difficulty and value.
Why do different tools show different search volumes?
Each tool estimates volume using its own data sources and models. Use one tool consistently to compare keywords, and treat the numbers as relative.
Is a keyword with zero search volume worth targeting?
Sometimes, yes. Tools often under-report very specific or new searches, so a “zero volume” keyword that clearly matches your offer can still bring useful visitors.
Previous lesson: Types of keywords: seed, short-tail, mid-tail and long-tail explained
Next lesson: Free keyword research tools: Google Keyword Planner, Google Trends and more