A keyword density checker analyzes your page content and tells you how often a target keyword appears relative to the total word count. The formula is straightforward: (number of times keyword appears ÷ total words) × 100. So if "Ottawa plumber" appears 8 times in a 400-word article, that's 2% density. These tools became popular in the early 2000s when search engines weighted exact-match keyword frequency heavily. Conventional wisdom said to hit 1-3% density for your primary keyword. Go higher and you'd risk a keyword stuffing penalty. Go lower and you supposedly wouldn't rank. That advice is mostly obsolete now. Google's algorithms understand semantic relationships, synonyms, and context through natural language processing. A page about "kitchen renovations" ranks fine without repeating that exact phrase 15 times. You'll naturally use variations like "remodel your kitchen," "cabinet upgrades," and "countertop installation." Still, keyword density checkers serve two practical purposes: - Catching accidental over-optimization when you've genuinely stuffed a keyword too many times, making content read awkwardly - Baseline content audits to see if a target term appears at all, especially on pages that aren't ranking despite decent backlinks At Ottawa SEO, we rarely check density as a standalone metric. If a client's page reads naturally to a human editor and covers the topic comprehensively, the keyword usually appears enough times organically. We're more concerned with whether the primary keyword is in the title tag, H1, first 100 words, and a few subheadings than hitting an arbitrary 2% threshold. The bigger risk today is under-optimization, not over-optimization. Pages targeting "commercial HVAC repair Toronto" that never mention those exact terms often underperform, even if they discuss related concepts. A density checker can confirm the phrase appears at least once or twice in natural positions. If you use one, treat anything above 3% as a red flag to rewrite for readability, and anything below 0.5% as a signal you might not be clearly focused on the topic. The tool is a diagnostic aid, not a target to hit.