Do keywords in the URL really affect Google rankings?

What is the actual weight of keywords in the URL?

Mueller explicitly describes this factor as "minor", indicating a signal of low intensity in the ranking algorithm. Google indeed uses this data to understand the subject of a page, but its influence on positions remains limited compared to major criteria like content, backlinks, or Core Web Vitals.

This statement confirms a practice observed for years: two pages that are strictly identical in content but have different URLs (one optimized and the other not) show no significant ranking difference. The signal exists, Google admits it, but its impact is negligible in real competition for positions.

Why prefer hyphens over underscores?

Google treats hyphens (-) as word separators, whereas underscores (_) are interpreted as join characters. In practice, "my-seo-page" will be understood as three distinct words, while "my_page_seo" will be read as a single composite term.

This technical difference dates back to the early generations of search engines and persists for historical compatibility reasons. Modern crawlers could technically handle both, but Google maintains this convention to avoid ambiguities in URL analysis.

Should this optimization be prioritized?

No, unless you are building a site from scratch. Modifying existing URLs to inject keywords leads to 301 redirects, a risk of temporary traffic loss, and consumes technical resources for a virtually negligible gain.

Optimization efforts should be focused on high-impact factors. An hour spent rewriting URLs would yield better returns if invested in improving content, fixing critical technical errors, or obtaining inbound links. The ROI of this micro-optimization is close to zero in a competitive context.

• Confirmed but marginal signal: keywords in the URL matter, but their weight is low
• Syntax to follow: hyphens (-) are mandatory for separating terms, no underscores (_)
• No overhaul necessary: do not modify existing URLs for this sole criterion
• Application on new sites: incorporate this best practice from the architecture design stage
• Priority hierarchy: focus on high-impact levers before this detail

Is this statement consistent with field observations?

Yes, it exactly matches what we observe in SERP analysis. Websites ranked on the first page present extremely varied URL profiles: some use numeric identifiers, others generic strings, and still others optimized URLs. No strong correlation emerges between the presence of keywords in the URL and the positions obtained.

Controlled A/B tests show that modifying only the URL of a page (with 301 redirect) without touching the content does not produce significant movement in rankings. The signal exists technically, Mueller confirms it, but its amplitude is lower than statistical noise in daily position variations.

What nuances should be added to this assertion?

The notion of "minor factor" remains vague. Google does not publish a weighting scale, and Mueller does not quantify what this "minor" entails. Based on documented experiments, it can be estimated that this signal represents less than 1% of the total weight of ranking factors for a given query.

Context is hugely important. In ultra-competitive queries where hundreds of factors differentiate positions, any micro-signal can theoretically tip a page. But in such cases, an optimized URL alone will never suffice: it must complement an already excellent overall profile. [To be verified]: no public data confirms that an optimized URL has ever moved a page from position 2 to position 1, all else being equal.

When does this rule not apply?

For e-commerce sites generating millions of dynamic URLs, the question doesn't even arise: technical parameters (filters, pagination, sessions) take precedence over semantic optimization. Platforms like Amazon rank perfectly with URLs containing alphanumeric identifiers, proving that the URL signal is negligible compared to other criteria.

Institutional sites or major media often retain inherited URL structures (dates, numeric categories) with no measurable negative impact. Their domain authority and content quality completely overshadow the micro-URL signal. Overhauling these structures to inject keywords would cost tens of thousands of euros in development for no gain.

What should I do practically on a new site?

When designing the architecture, adopt a semantic and readable URL structure: /category/sub-category/main-keyword. Use hyphens exclusively to separate terms, in lowercase, without accents or special characters. Limit depth to a maximum of 3-4 levels to avoid dilution of internal PageRank.

Follow these conventions from the start, as they also simplify developers' work and future maintenance. A clean URL facilitates analytical tracking, debugging, and communication with clients. The SEO benefit remains minimal, but the initial effort is negligible compared to a later overhaul.

What mistakes should be avoided at all costs?

Do not launch a massive URL migration solely to optimize this criterion. 301 redirects generate a temporary loss of crawl budget, risks of technical errors, and consume resources for a near-zero ROI. Each redirect also consumes some PageRank "juice", even though Google claims that the loss has become negligible.

Avoid overloaded keyword URLs like /running-shoes-men-cheap-nike-adidas. Google detects this stuffing, and it degrades the user experience by making URLs unreadable. Aim for clarity and conciseness: /running-shoes-men is quite sufficient. The page content will do the rest.

How can I check if my site is compliant?

Crawl your site with Screaming Frog or Oncrawl, export the list of URLs, and filter those containing underscores, special characters, or incomprehensible numeric identifiers. Prioritize correcting strategic URLs (high-traffic pages, key commercial pages) if you need to intervene.

Also verify consistency: if your site mixes hyphens and underscores across sections, standardize during the next technical overhaul. But remember that this task should never be prioritized over indexing, speed, or weak content issues.

• Use hyphens (-) exclusively to separate words in URLs
• Adopt a readable and semantic structure from the site's creation
• Do not initiate a URL migration solely for this criterion on an existing site
• Avoid keyword stuffing in URLs: 3-5 words maximum
• Prefer lowercase, without accents, without special characters
• Limit depth to 3-4 levels to preserve PageRank transmission