Readiness check · Accelerate lane · weight 6

Static files cached for 30 days or more

The first same-site stylesheet or script on the homepage is served with max-age of at least 30 days or the immutable directive.

Observed on: 51%
Top 1K sites: 51%
Top 1M band: 51%
Not measured: 15,517

Why it matters

Returning visitors and later page views reuse cached files instead of downloading them again.

How to fix it

Give versioned (fingerprinted) CSS, JavaScript, fonts and images Cache-Control: public, max-age=31536000, immutable, and change the file name whenever the content changes.

How we check

The first same-site stylesheet or script on the homepage is served with max-age of at least 30 days or the immutable directive.

Observed: Long-lived caching on static files.

Not observed: Static files cached briefly or not at all.

Limit: Read from the homepage response only; other pages or regions may send different headers.

Stack-specific steps

Cloudflare: Use Cache Rules to set edge and browser TTLs for static file paths.
WordPress: Caching plugins or your host can set long browser cache lifetimes for theme and plugin assets.

By popularity band

Chrome UX Report band	Observed	Measured
Top 1K	51%	187
Top 5K	52%	1,033
Top 10K	52%	1,362
Top 50K	51%	10,935
Top 100K	52%	3,376
Top 500K	52%	3,608
Top 1M	51%	4,077

Static files cached for 30 days or more

Why it matters

How to fix it

How we check

Stack-specific steps

By popularity band

Categories most likely to do this

Categories least likely

By stack

By provider

Popular sites where we observed this

Sources and guides