How the test works
The checker downloads the page three times: once without compression, once asking for gzip and once asking for Brotli. It compares the bytes actually sent, so you see the real saving.
Typical results
- Gzip usually reduces HTML by 60–80 %.
- Brotli is typically another 15–25 % smaller than gzip for text files.
- Images, videos and fonts such as WOFF2 are already compressed and should not be compressed again.
How to enable compression
- Apache: enable mod_deflate (gzip) and mod_brotli.
- nginx:
gzip on;plus the ngx_brotli module. - CDNs such as Cloudflare enable Brotli automatically or with one switch.
Compression is one of the easiest speed wins. Measure the full effect with the Website Speed Test.
Frequently asked questions
Is Brotli better than gzip?
Yes for text files: Brotli produces smaller files and all modern browsers support it. Keep gzip enabled as a fallback.
Why is compression not detected?
It may be disabled on the server, or the response is too small to be compressed. Some servers only compress certain content types.
Does compression help SEO?
Indirectly. Smaller downloads improve load time and Core Web Vitals, which are part of Google's page experience signals.