How Many Keywords to Use for SEO: Finding the Perfect Balance

TL;DR

For optimal SEO, each page on your website should focus on one primary keyword. This core term should be supported by two to five secondary keywords, which are variations or conceptually related phrases. This strategy helps search engines understand your content's focus while allowing you to rank for a broader range of queries. Ultimately, modern SEO prioritizes creating high-quality content that satisfies user intent over hitting arbitrary keyword counts.

The Core Rule: Focus on a Single Primary Keyword

In the complex world of SEO, one principle remains refreshingly simple: each page should target one main topic, represented by a single primary keyword. A primary keyword is the main phrase you want a page to rank for, the term that best summarizes its content. For example, if your page is about caring for indoor ferns, your primary keyword might be “how to care for indoor ferns.” This focused approach is the foundation of effective on-page SEO.

The rationale behind the “one page, one primary keyword” rule is clarity. When a page is tightly focused on a single topic, it sends a clear signal to search engines like Google about its purpose. This eliminates ambiguity, preventing your page from being lost in the digital noise. Trying to rank for multiple, unrelated primary keywords on the same page—such as “indoor fern care” and “best outdoor garden hoses”—dilutes your message and confuses both search engines and users. This can lead to a phenomenon known as keyword cannibalization, where your own pages compete against each other in search results, weakening the ranking potential of both.

Adhering to this rule also prevents the outdated and penalized practice of "keyword stuffing," which involves unnaturally forcing keywords into content. Instead of asking "how many keywords can I fit in?" the better question is "what is the single most important query this page should answer?" By identifying and committing to one primary keyword before you even start writing, you ensure your content remains relevant, authoritative, and valuable to the user searching for that specific topic.

Expanding Your Reach with Secondary Keywords

While a single primary keyword provides focus, relying on it alone is like fishing with a single hook. To maximize your reach, you need to use secondary keywords. These are variations, synonyms, or thematically related terms that add context and depth to your content. For instance, if your primary keyword is “best running shoes for beginners,” secondary keywords could include “comfortable running sneakers,” “rookie runner footwear,” or “what to look for in running shoes.” A good rule of thumb is to include two to five of these supporting phrases per page.

Secondary keywords, including LSI (Latent Semantic Indexing) keywords, help search engines better understand the nuances of your topic. They create a rich semantic web around your primary keyword, signaling to Google that your content is comprehensive. This not only strengthens your page's authority on the main topic but also allows you to capture traffic from a wider array of long-tail searches—the more specific, less common queries that often show higher purchase intent.

The ideal number of keywords often correlates with content length. A common guideline, supported by data from search engine results pages, is as follows:

• 300-500 words: 1 primary keyword, 1-2 secondary keywords
• 500-1,000 words: 1 primary keyword, 2-3 secondary keywords
• 1,000-2,000+ words: 1 primary keyword, 3-5+ secondary keywords

This structure ensures your content remains focused yet comprehensive. Finding these secondary terms involves brainstorming and using keyword research tools. For those looking to scale their content creation, platforms like BlogSpark can be invaluable. Its AI-powered tools help discover relevant keywords and generate optimized articles, streamlining the process of building out topically rich content that meets these guidelines efficiently.

Beyond the Count: Prioritizing User Intent and Quality

While knowing the right number of keywords is a great starting point, modern SEO has evolved far beyond a simple numbers game. Today, the most critical factors for ranking are content quality and how well you satisfy user intent. As experts at Moz emphasize, it's more effective to capture the different intents behind a topic rather than just collecting a long list of keywords. User intent refers to the ultimate goal a person has when they type a query into a search engine—are they looking to learn, buy, or find a specific site?

Some discussions in SEO mention keyword density, which is the percentage of times a keyword appears on a page. While a historical guideline might suggest a density of 1-2%, this metric is largely outdated. Over-focusing on density can lead to keyword stuffing, where keywords are repeated so often that the text becomes unnatural and difficult to read. For example, writing, “Our best running shoes are the best running shoes for runners who want the best running shoes,” is a clear example of stuffing that offers a poor user experience and can be penalized by search engines.

Instead, the goal should be to write naturally and comprehensively for your human audience. Your primary and secondary keywords should fit seamlessly into the text, serving the content rather than dictating it. A practical test is to read your content aloud. If it sounds robotic or forced, you’ve likely over-optimized. The true measure of success is creating a page that thoroughly and clearly answers the user's question, providing genuine value. When you prioritize the user experience, positive engagement signals like longer time on page and lower bounce rates will follow, which are powerful indicators to Google that your page is a high-quality result.