Google Uses About 40 Signals To Determine Canonical URLs

In a recent episode of Google’s Search Off the Record podcast, Allan Scott from the “Dups” team explained how Google decides which URL to consider as the main one when there are duplicate pages.

Google looks at about 40 different signals to pick the main URL from a group of similar pages.

Around 40 Signals For Canonical URL Selection

Duplicate content is a common problem for search engines because many websites have multiple pages with the same or similar content.

Google uses canonicalization to pick one URL as the main version to index and show in search results.

Some of the known signals include rel=”canonical” tags, 301 redirects, HTTPS vs. HTTP, sitemaps, internal linking, and URL length.

Balancing Signals

With conflicting signals, Google falls back on lesser signals to determine the canonical URL.

Strong signals like rel=”canonical” tags and 301 redirects are crucial, but other factors can come into play when signals are unclear.

Best Practices For Canonicalization

Clear signals help Google identify the preferred canonical URL.

Best practices include using rel=”canonical” tags correctly, implementing 301 redirects, ensuring HTTPS versions are accessible, submitting sitemaps with preferred URLs, and maintaining consistent internal linking.

Mistakes To Avoid

1. Incorrect or conflicting canonical tags

Fix: Double-check canonical tags, use only one per page, and use absolute URLs.

2. Canonical chains or loops

Fix: Ensure canonical URLs point to the final, preferred version of the page.

3. Using noindex and canonical tags together

Fix: Use canonical tags for consolidation and noindex for exclusion.

4. Canonicalizing to redirect or noindex pages

Fix: Canonical URLs should be 200 status and indexable.

5. Ignoring case sensitivity

Fix: Keep URL and canonical tag casing consistent.

6. Overlooking pagination and parameters

Fix: Use canonical tags pointing to the first page or “View All” for pagination, and keep parameters consistent.

Key Takeaways

• Google uses approximately 40 different signals to determine canonical URLs
• When signals conflict, Google falls back on secondary signals
• Clear, consistent implementation of canonicalization signals is crucial
• Common mistakes can confuse search engines

FAQs

1. How many signals does Google use to determine canonical URLs?

Google uses around 40 different signals.

2. What are some best practices for canonicalization?

Best practices include using rel=”canonical” tags correctly, implementing 301 redirects, and maintaining consistent internal linking.

3. What are common mistakes to avoid in canonicalization?

Common mistakes include incorrect or conflicting canonical tags, canonical chains or loops, and overlooking pagination and parameters.

4. How does Google handle conflicting signals?

Google falls back on lesser signals to determine the canonical URL.

5. Why is clear implementation of canonicalization signals important?

Clear implementation helps Google identify the preferred canonical URL, improving site crawling, indexing, and search visibility.