Sitemap priority, changefreq and lastmod
Three optional tags, three very different fates at Google: one matters when it is honest, two are ignored.
Tap a tag: what does Google actually read?
Protocol: When the page content last changed, in W3C Datetime format (a date, or a full timestamp with timezone).
Google: Google says it uses lastmod when it is consistently and verifiably accurate, for example matching the real last significant change. Stamping every URL with the build time teaches Google to ignore it.
The short answer
Google’s Build and submit a sitemap page says Google ignores <priority> and <changefreq> values, and uses <lastmod> if it is consistently and verifiably accurate. Google’s 2023 announcement deprecating the sitemap ping endpoint repeated the point: lastmod is the tag worth getting right.
What priority was meant to do
The sitemaps.org protocol defines priority as the importance of a URL relative to other URLs on the same site, from 0.0 to 1.0 with a default of 0.5. It never compared your pages with anyone else’s, which is why setting every page to 1.0 was always self-defeating: if everything is top priority, nothing is. Today it doesn’t matter at Google either way.
How to set lastmod properly
- Use the date the main content last changed meaningfully: text, key images, structured data, important links.
- Don’t bump it for template changes, a new copyright year, or a comment count.
- Don’t stamp the sitemap generation time on every URL. The sitemap checker flags files where every lastmod is identical, and future dates.
- Use W3C Datetime:
2026-09-18or2026-09-18T14:30:00+00:00. - Keep the HTTP
Last-Modifiedheader and any visible “updated” date consistent with it.
Tracking lastmod over time
The easiest way to see whether your CMS writes honest dates is to save today’s sitemap and compare it with next week’s. If hundreds of URLs were re-dated and you only edited three articles, the generator needs fixing.
Questions
Does sitemap priority affect rankings?
No. Priority only ever described relative importance within your own site, and Google states that it ignores the priority value entirely. It has no effect on rankings.
Does Google use changefreq?
No. Google ignores changefreq. It decides how often to recrawl based on its own signals, which can include an accurate lastmod.
What lastmod format should I use?
W3C Datetime: a date such as 2026-09-18, or a full timestamp with a timezone such as 2026-09-18T14:30:00+00:00. Don’t use local formats like 18/09/2026.
Should lastmod change when I update the footer or sidebar?
No. Google’s guidance is that lastmod should reflect the last significant update to the page’s main content, structured data or links, not a copyright year or a sitewide template change.
Should I remove priority and changefreq from my sitemap?
You don’t have to; valid values are harmless and Bing or other crawlers may read them. Removing them makes files smaller and removes the temptation to maintain values that do nothing at Google.