Brotli vs Gzip compression explained
TL;DR: Both Brotli and Gzip compress text-based assets, HTML, CSS, JavaScript, before sending them to the browser, reducing transfer size and improving load time. Brotli generally achieves smaller output than Gzip at comparable or even lower compression levels, particularly for typical web content, making it the better default where supported. Gzip remains near-universally supported and is the sensible fallback for any client or intermediary that does not support Brotli, meaning a well-configured server serves Brotli where the browser supports it and falls back to Gzip otherwise, rather than choosing one exclusively.
What compression actually does for a website
Text-based web assets, HTML markup, CSS stylesheets, JavaScript files, compress very effectively because they contain a lot of repetitive structure and predictable patterns, unlike already-compressed binary formats like JPEG images or video, which gain little to nothing from further compression. Server-side compression takes these text assets and encodes them into a meaningfully smaller form before transmission, with the browser decompressing them automatically on arrival, directly reducing the amount of data that needs to travel over the network and therefore reducing load time, particularly noticeable on slower or higher-latency connections.
Gzip: the long-established default
Gzip has been the standard, near-universally supported compression method for web content for a very long time, meaning virtually every browser, proxy, and intermediary correctly supports it without exception, making it the safe, reliable baseline every properly configured server should have enabled at minimum. Its compression ratio for typical text-based web content is strong, though generally somewhat less efficient than Brotli's typical output at comparable settings.
Brotli: generally smaller output
Brotli, developed more recently specifically with web content compression in mind, generally achieves smaller compressed output than Gzip for the same source content, particularly for typical HTML, CSS, and JavaScript, meaning switching from Gzip to Brotli where supported produces a real, if often modest, additional reduction in transfer size without requiring any change to your actual content. Brotli support among current browsers is now very broad, essentially universal among actively maintained modern browsers, though a small share of older or unusual clients may lack support, which is exactly why proper configuration serves Brotli conditionally rather than exclusively.
Where the compression gap actually matters
The practical difference between Brotli and Gzip scales with how much text-based content a given page actually transfers, meaning a text-heavy, script-heavy page (a complex web application, a page with substantial custom JavaScript) sees a more meaningful absolute byte-size benefit from switching to Brotli than a simple, mostly-image page where text assets are already a small share of total page weight, covered more broadly in our full slow WordPress diagnostic guide. For most typical WordPress sites, the benefit is real but generally secondary to larger factors like image optimization and server-side caching, worth implementing as a low-effort addition once those higher-impact factors are already addressed.
Compression level trade-offs
Both Gzip and Brotli support configurable compression levels, trading more aggressive compression (smaller output) against more CPU processing time required to actually perform that compression. At very high compression levels, the CPU cost can become disproportionate to the additional size reduction gained, particularly for dynamically generated content compressed on every request rather than static assets compressed once and cached. A reasonable, moderate compression level, rather than the maximum available setting, is generally the sensible default for dynamic content, while static assets (which can be pre-compressed once and served repeatedly without needing to recompress on every request) can reasonably use a higher compression level without the same recurring CPU cost concern.
A comparison table
| Factor | Gzip | Brotli |
|---|---|---|
| Browser support | Universal | Very broad, essentially universal on current browsers |
| Typical compression ratio | Strong | Generally somewhat better |
| CPU cost at high compression levels | Moderate | Generally somewhat higher at max settings |
| Recommended configuration | Always enabled as baseline/fallback | Enabled where supported, serving Gzip as fallback |
How to check what your server is currently using
Browser developer tools' Network tab shows the Content-Encoding response header for a given request, directly confirming whether Brotli (br) or Gzip (gzip) was actually used for that specific response, a quick, direct way to verify your server's actual current configuration rather than assuming based on your hosting provider's general marketing claims.
FAQs
Do I need to choose one exclusively, Brotli or Gzip?
No, and you should not; a properly configured server offers both, serving Brotli to clients that support it and falling back to Gzip for those that do not, based on what the browser indicates it supports in its request headers.
Does enabling Brotli require any changes to my actual website content?
No, compression is applied automatically at the server level to your existing content as it is transmitted; no changes to your HTML, CSS, or JavaScript source files are required to benefit from switching to or adding Brotli support.
Does compressing images with Brotli or Gzip help reduce their file size?
No, images (particularly already-compressed formats like JPEG and modern formats like WebP, covered in our dedicated guide) gain little to nothing from this kind of text-oriented compression, since they are already compressed using image-specific algorithms; Brotli and Gzip are specifically valuable for text-based assets.
Does my hosting provider need to specifically support Brotli, or can I enable it myself?
This depends on your specific hosting setup; on managed or shared hosting, Brotli support depends on whether your host's server configuration includes it, while on a VPS with full server access, you can typically enable it yourself through your web server's configuration.
Is there a meaningful difference in decompression speed on the visitor's end?
Decompression is generally fast and not a meaningful bottleneck for either method on virtually any modern device, meaning the practical performance consideration is almost entirely about compression ratio and server-side compression cost, not decompression speed on the visitor's side.
Does using a CDN change how compression is handled?
Many CDN providers handle compression at their edge, potentially applying Brotli or Gzip independently of your origin server's own configuration, worth checking your specific CDN's settings if you are using one, since this can mean your CDN handles compression even if your origin server itself is not separately configured for it.
Is there any downside to enabling Brotli alongside Gzip?
Minimal; the main consideration is ensuring your server is genuinely correctly configured to negotiate between the two based on client support rather than serving Brotli to a client that cannot decompress it, which would break the response entirely, a configuration detail any reputable web server software handles correctly by default when Brotli support is properly enabled.
Conclusion
Brotli generally compresses text-based web content somewhat more efficiently than Gzip, making it the better default where supported, while Gzip remains the essential, universally compatible fallback ensuring every client can still receive properly compressed content regardless of Brotli support. A properly configured server serves both conditionally rather than choosing one exclusively, and this is a low-effort, worthwhile addition to a broader performance strategy once higher-impact factors like caching and image optimization are already addressed.
HostCloud's hosting includes both Brotli and Gzip compression configured correctly by default, giving your site the smaller transfer sizes both methods provide without requiring manual server configuration on your part. Plans start at ₹99 a month at https://hostcloud.in.