What a sitemap is for
An XML sitemap is a list of the URLs on your site that you want search engines to know about. It helps with discovery — particularly for pages that are not well linked internally, and for large or newly launched sites.
It is worth being clear about what it does not do. A sitemap is a suggestion, not an instruction: listing a URL does not guarantee it will be crawled, and certainly does not guarantee it will be indexed. It also does not improve rankings. It helps Google find pages; whether they are worth indexing is decided elsewhere.
The limits
The sitemap protocol sets hard limits, and this tool warns when you approach them.
XML sitemap limits and rules
| Rule |
Limit |
| URLs per sitemap file |
50,000 |
| Uncompressed file size |
50 MB |
| Sitemaps per sitemap index |
50,000 |
| Encoding |
UTF-8, with URL-escaped entity characters |
| URL scope |
All URLs must share the sitemap's host |
priority |
A decimal from 0.0 to 1.0 |
changefreq |
always, hourly, daily, weekly, monthly, yearly or never |
The mistakes that actually cost you
Some of these are XML errors this tool will catch; others are perfectly valid XML that still undermines the sitemap. Both are worth checking.
- Listing noindexed URLs. A sitemap says "please index this" and a noindex tag says the opposite. Pick one — usually by removing the URL from the sitemap.
- Listing redirects or 404s. Every URL should return 200. Redirect chains in a sitemap waste crawl budget and signal neglect.
- Listing non-canonical URLs. Only include the canonical version of each page, or you are asking Google to index the duplicate.
- Mixing http and https, or www and non-www. Every URL must match your canonical host exactly.
- A stale
lastmod. Setting every entry to today on every build makes the field worthless; Google learns to ignore it.
- Over-thinking
priority. Google has said it largely ignores it. It is optional; if the values are all 0.8 it is telling nobody anything.
- Unescaped ampersands. A raw
& in a URL breaks XML parsing outright.
- A sitemap not referenced in robots.txt, which is one of the two ways search engines find it at all.
When to split into a sitemap index
Once a site passes a few thousand URLs, one file stops being convenient even though it is still legal. A sitemap index is a sitemap of sitemaps: split by content type — products, articles, categories — and you can see in Search Console which section has coverage problems rather than one aggregate figure.
Splitting is required above 50,000 URLs or 50 MB. Doing it earlier, by type, is a diagnostic decision rather than a technical one.
After validating
A sitemap that parses cleanly is the starting point, not the finish. Reference it in your robots.txt, submit it in Google Search Console, and then watch the coverage report — that is where you learn which listed URLs were actually indexed and why the rest were not.
Resubmit after meaningful structural changes, not on a schedule. Search engines re-fetch sitemaps on their own.