Sitemap priority, changefreq and lastmod
The protocol offers three optional tags. Google reads one of them, and only when it's honest. Here's what each does, what search engines actually use, and how to write lastmod correctly.
The short answer
| Tag | Protocol meaning | |
|---|---|---|
lastmod | When the page last changed | Used, if consistently accurate |
changefreq | How often it probably changes (always … never) | Ignored |
priority | Importance relative to your other URLs, 0.0–1.0 (default 0.5) | Ignored |
Why priority never worked the way people hoped
Priority was always relative within your own site, never compared with other sites. And because most generators wrote 1.0 or 0.8 on everything, it carried almost no information. Search engines stopped relying on it long ago.
Why changefreq was dropped
It is a guess about the future, and crawlers can measure the past. They see how often a page actually changes on each visit, which beats any declared frequency.
What makes lastmod useful
It is a fact, not a forecast, and it can be checked. When a crawler sees lastmod move and then finds genuinely new content, trust grows. When lastmod moves on every deploy and the page is the same, the tag is ignored for the whole site. The demo shows the difference.
<url> <loc>https://example.com/guide</loc> <lastmod>2026-09-21</lastmod> <changefreq>daily</changefreq> <priority>1.0</priority> </url>
Four tags, each apparently a signal. Now switch viewpoint.
Does your lastmod deserve trust?
Top row: weeks the page really changed. Bottom row: weeks lastmod moved (green = matched a real edit, red = false alarm).
Every bump means something, so a crawler that follows lastmod wastes nothing. This is the pattern Google says it rewards.
Writing lastmod correctly
Valid W3C Datetime forms, from least to most precise: 2026, 2026-09, 2026-09-21, 2026-09-21T14:05+02:00, 2026-09-21T14:05:00+02:00, 2026-09-21T12:05:00Z. A plain date is fine for most sites. Add a time only if pages change several times a day.
Paste whatever your CMS or database gives you into the formatter: Unix timestamps, SQL datetimes or written dates. It returns a valid value and refuses to guess on ambiguous formats like 03/04/2026.
lastmod formatter
Questions people ask
Does Google use sitemap priority?
<priority> and <changefreq>. Leaving them out makes the file smaller and loses nothing with Google.Does Bing use priority or changefreq?
lastmod rather than changefreq and priority, and has urged site owners to keep lastmod accurate.What format does lastmod need?
2026-09-21) or a full timestamp with timezone (2026-09-21T14:05:00+00:00). A time without a timezone, or a local format like 21/09/2026, is invalid.When should lastmod change?
Should I remove priority and changefreq from an existing sitemap?
priority 1.0 on every URL, removing it saves bytes and removes a signal that says nothing.