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sitemap lastmod

20 established claims

Verdict

Google uses the sitemap <lastmod> element as a signal for scheduling crawls to previously discovered URLs, and its documentation as of 2026-07-08 says Google uses the value if it is consistently and verifiably accurate. The signal is treated as binary, so incorrect lastmod dates risk being ignored completely; on 16 July 2026 Gary Illyes said a site is better off not using lastmod dates if those dates are wrong. The value should reflect the last significant update, not trivial changes such as sidebar, footer, or copyright date updates, and it is fine to omit lastmod for pages whose last modification date cannot be easily determined.

Written from the 20 established claims below, then checked against them. How that works.

Documented position12

What the operator of the system says in its own documentation.

Google's "Build and submit a sitemap" documentation states that…

  • the <lastmod> value should reflect the date and time of the last significant update to the page.
  • an update to the copyright date is not significant.
first-party
1 quote from 1 source
The <lastmod> value should reflect the date and time of the last significant update to the page. For example, an update to the main content, the structured data, or links on the page is generally considered significant, however an update to the copyright date is not.

Google's Search Central blog post 'Sitemaps ping endpoint is going away' states that if a site's lastmod element does not consistently match reality, Google will eventually stop believing the site about the last modified date of its pages.

first-party
1 quote from 1 source
it needs to consistently match reality: if your page changed 7 years ago, but you're telling us in the lastmod element that it changed yesterday, eventually we're not going to believe you anymore when it comes to the last modified date of your pages

Google's Search Central blog states that a site can use a lastmod element for…

  • all the pages in its sitemap.
  • just the pages it is confident about.
first-party
1 quote from 1 source
You can use a lastmod element for all the pages in your sitemap, or just the ones you're confident about.

Google's Search Central blog states that where site software cannot easily tell the last modification date of a page, it is fine to leave out lastmod for those pages.

first-party
1 quote from 1 source
some site software may not be able to easily tell the last modification date of the homepage or a category page because it just aggregates the other pages on the site. In these cases it's fine to leave out lastmod for those pages.

Google's Search Central blog states that…

  • when Google says 'last modification' in the context of sitemap lastmod it means 'last significant modification'.
  • an insignificant change to sidebar or footer text does not require updating the lastmod value.
first-party
1 quote from 1 source
And when we say "last modification", we actually mean "last significant modification". If your CMS changed an insignificant piece of text in the sidebar or footer, you don't have to update the lastmod value for that page.

Google's Search Central blog states that in the case of Google Search, the vast majority of unauthenticated sitemap submissions lead to spam.

first-party
1 quote from 1 source
Our internal studies-and also other search engines such as Bing -tell us that at this point these unauthenticated sitemap submissions are not very useful. In fact, in the case of Google Search, the vast majority of the submissions lead to spam.

Measured finding1

Something someone actually measured, with the method attached.

Google's Search Central blog states that, based on Google's internal studies, the sitemap priority element generally doesn't accurately reflect the actual priority of a page relative to other pages on a site.

first-party
1 quote from 1 source
The priority element is a heavily subjective field and based on our internal studies, it generally doesn't accurately reflect the actual priority of a page relative to other pages on a site.

Practical effect3

What is observed to happen in practice, as distinct from what is documented.

The Bluesky post at bsky.app/profile/methode.bsky.social states that…

  • a site is probably better off without the lastmods.
  • leaving out lastmods at least saves a few bytes.
medium confidenceother
1 quote from 1 source
probably better off without the lastmods. at least you save a few bytes

Google's Search Central blog states that Google uses the sitemap lastmod element as a signal for scheduling crawls to URLs it previously discovered.

first-party
1 quote from 1 source
nowadays lastmod is indeed useful in many cases and we're using it as a signal for scheduling crawls to URLs that we previously discovered

Changed on2

A dated change. This is where advice quietly stops being true.

Google announced on 26 June 2023 that…

  • it was deprecating its support for the sitemaps ping endpoint.
  • the sitemaps ping endpoint would stop functioning in 6 months.
first-party
2 quotes from 1 source
we're deprecating our support for sitemaps ping and the endpoint will stop functioning in 6 months
Monday, June 26, 2023

Echoed without a primary source2

Widely repeated in the field, but traceable only to other repetitions. Listed because knowing something is merely echoed is worth as much as knowing it is documented.

Search Engine Roundtable reported on 16 July 2026 that Gary Illyes of Google said on Bluesky that a site is better off not using a lastmod date in its XML sitemap if those dates are wrong.

medium confidencetrade press
2 quotes from 1 source
Gary Illyes from Google said that you are better off not using a lastmod date in your XML Sitemap if those dates are wrong. He said on Bluesky , "probably better off without the lastmods. at least you save a few bytes."
Jul 16, 2026

Search Engine Journal reported that Google treats the sitemap lastmod signal as binary, meaning the signal is either trusted or not.

medium confidencetrade press
3 quotes from 1 source
Google treats lastmod as binary - trusted or not.
Incorrect lastmod dates risk the signal being ignored completely.
June 11, 2024