Sitemap lastmod, priority and changefreq
Three optional tags, and only one of them still matters. Here is what each was meant to do, what Google and Bing actually do with it, and what to put in yours.
Last updated
Which sitemap tags do search engines use?
Only lastmod, and only when it is accurate. Google: “Google ignores <priority> and <changefreq> values”, and “Google uses the <lastmod> value if it’s consistently and verifiably accurate” (Google’s guide to building a sitemap). Bing says “changefreq and priority are ignored by Bing” (Bing’s July 2025 sitemap guidance).
| Tag | Meant to say | What Google and Bing do |
|---|---|---|
lastmod | When the page last changed | Use it to decide what to recrawl, if it has been reliable |
priority | How important a page is relative to your others, 0.0 to 1.0 | Ignore it |
changefreq | How often the page changes, from always to never | Ignore it |
What should lastmod be?
The date of the page’s last significant change: the main content, structured data or links. Google’s guide says a change to a copyright date in the footer is not significant. Google’s 2023 note put it this way: lastmod has to “consistently match reality” (Google’s June 2023 announcement).
The most common mistake is stamping every URL with the date the sitemap was built. Bing: “the date must be set to the date the linked page was last modified, not when the sitemap is generated” (Bing’s note on lastmod). A sitemap where every page changed today teaches the search engine to stop trusting your dates.
| Good lastmod | Bad lastmod |
|---|---|
| The date an article was last edited | Today’s date on every URL |
| Taken from the CMS or the page’s dateModified | The time the sitemap file was regenerated |
| Left out when you do not know it | A guess, or a date in the future |
What date format does lastmod use?
The W3C Datetime format, which the sitemaps.org protocol specifies. The date alone is enough: YYYY-MM-DD, such as 2026-10-17. If you add a time, include the time zone, such as 2026-10-17T09:30:00+00:00. A date in another style, like 17/10/2026, is not valid.
Should you remove priority and changefreq?
You do not have to. They are valid, and the search engines simply skip them. But there is no reason to maintain them either, and some generators fill them in automatically in ways that mean nothing. Leaving them out keeps the file smaller and honest.
How do our tools handle these tags?
The sitemap generator never writes priority or changefreq, and writes lastmod only from a date the site gives: the page’s own dateModified, or a server Last-Modified that is not simply the time of the request. The validator warns when every lastmod in a sitemap is the same date.
Frequently asked questions
Does a higher priority make a page rank better?
No. Google and Bing ignore the priority tag entirely.
Should lastmod include the time?
Either is valid. A date alone is fine for most sites; Bing recommends a full date and time where you have it.
Do I need lastmod at all?
It is optional. Add it only if you can keep it accurate; an absent lastmod is better than a wrong one.
What counts as a significant change?
A change to the main content, the structured data or the links on the page. A new copyright year or a sidebar tweak does not count.