GZIP vs Brotli Compression: Which One Is Best for Web Performance in 2025?
Compare GZIP vs Brotli compression to see which delivers faster load times, better efficiency, and smoother web performance.
You push a change, hit refresh, and the page hesitates. Not forever, just long enough to feel sticky. You cannot ship less HTML, CSS, or JavaScript every time, but you can ship smarter.
You have two levers to pull right away: gzip and Brotli. Pull the right one and the page pops into view like a curtain lift. Pull the wrong one and the audience waits.
Key Takeaways
- Use Brotli for static assets that you can precompress during build or at the CDN. It makes files smaller than gzip and browsers support it widely.
- Use Gzip for highly dynamic responses when you care most about Time to First Byte. If you are ready to test, try Brotli at a low or mid level for some APIs and dynamic HTML. Results vary by payload, so measure.
Your job is to pick the right tool for the right kind of bytes, every single time.
What is Brotli and Gzip Compression?
Both gzip vs brotli are lossless. They squeeze text without losing a single character, which keeps your pages correct and your scripts safe. Under the hood, both rely on the same core ideas.
- First, an LZ77 style search replaces repeats with pointers.
- Then, Huffman coding turns common symbols into short codes and rare symbols into longer ones.
This combo is called DEFLATE for gzip, and a modernized version of the same ideas for Brotli. You do not need all the math. Just remember that both find duplicates and then store the results efficiently.
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What Makes Brotli Different from GZIP
You will hear “Brotli compresses better.” Here is why, in plain terms.
- A bigger memory of the past: Gzip looks for repeats in a small 32 KiB sliding window. Brotli can look much further back, up to about 16 MiB, which helps on long bundles where the same strings show up again and again.
- A built‑in dictionary: Brotli ships with a static dictionary of common web terms. Think HTML tags, CSS tokens, and snippets you see in many apps. With transforms like “add suffix” or “change case,” that small dictionary explodes into lots of useful matches. This is a big win for small files, and it helps from the very first byte.
- Smarter context for literals: Brotli can pick different Huffman tables based on nearby bytes, which makes literal characters cheaper to store. In plain English, it guesses better what is coming next.
These three edges explain why brotli compression usually beats gzip on size.
Brotli vs GZIP Performance - Data
Smaller is good, but speed depends on round trips as well as bytes. If both the gzip and Brotli versions fit into the same number of TCP round trips, your transfer time can look the same even if Brotli is smaller.
The biggest wins show up when Brotli pushes a file under a round‑trip threshold. That is why results vary by asset and by latency.
1. File Size
Across many studies and real sites, Brotli produces smaller payloads than gzip for HTML, CSS, and JS.
Akamai’s well‑known benchmark reported median savings of 82% with Brotli vs 78% with gzip across a large sample, and bigger gains on HTML, CSS, and JS individually.
Smaller files mean less bandwidth every time.
2. Compression Speed
The smaller size is not free. Brotli at very high levels is slow to compress.
Recent tests show the gap clearly.
- On a ~1.6 MB JavaScript file, Brotli took about 1.8 s at its chosen level while gzip took 0.05 s.
- On a ~523 MB JSON file, Brotli took ~759 s while gzip took ~5.7 s.
That is fine for build time or once‑per‑edge caching, but painful for per‑request work.
3. Decompression Speed
Good news for users. Decompression is similar between the two, so you do not slow the browser by choosing Brotli. The client pays roughly the same CPU cost either way.
That is why pushing the heavy work to build or to the CDN is a nice move.
4. Use Impact
This part depends on your files and your network shape.
- Harry Roberts tested sites and saw modest but real gains from Brotli over gzip. Median First Contentful Paint improved by about 3.5% when moving from gzip to Brotli.
The big jump was from no compression to gzip. That lines up with what you feel: the first step is huge, the second is smaller but still helpful. - OYO reported a much larger win after switching to Brotli for JS and CSS, with ~37% latency improvement and seconds saved at the 50th and 90th percentiles.
If your payload is big and very repetitive, the gains can be dramatic.
Static vs Dynamic Compression
When you decide brotli vs gzip, start with this split. It keeps your mental model simple and your results predictable.
Static Assets You can Precompress
Examples include JS bundles, CSS, SVG, fonts, and static HTML.
- Precompress with Brotli at a high level during your build or deploy.
- Serve the .br files directly from your origin or let the CDN cache them.
Cloudflare compresses on the edge at a conservative level by default, but it can also cache Brotli from origin, which lets you ship max‑quality assets to the edge and avoid CPU at request time.
NGINX and Apache both support serving precompressed .br files so the server does zero work per request.
Why this works: you pay the slow compression once. Everyone enjoys faster downloads many times. Decompression on the client is fast either way.
Dynamic Responses You Compress on the Fly
Think personalized HTML, search results, or chatty JSON.
- Start with gzip at a mid level if TTFB is tight. It is quick to compress and easy to reason about.
- Try Brotli at a low or mid level for specific endpoints. In many cases it matches or beats gzip size with similar speed, but you should test on your data and your hardware.
If you use a CDN, you can let it compress dynamic responses at the edge with a moderate Brotli level. This balances CPU and size without touching your origin.
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Brotli vs Gzip for Render Blocking Assets
Render blocking assets decide when a user sees the first paint. HTML, CSS, and the first JavaScript are the gatekeepers. If they move faster, the whole page feels fast.
Here is how to think about brotli vs gzip performance for those files.
- If the file is static and cacheable, brotli compression usually gives you a smaller payload than gzip. The browser decodes it quickly, and the edge can cache it. Your users wait for fewer bytes, which helps First Contentful Paint and Largest Contentful Paint.
- If the response is dynamic and you compress on the fly, gzip is often safer for Time to First Byte. If you have CPU headroom, try Brotli at a low or mid level on a few hot endpoints and measure. Some APIs win. Others do not.
A simple way to apply this without stress:
- Precompress render blocking CSS and the main JS bundle with Brotli at a high level during build, and serve the .br files when the browser asks for br.
- Keep .gz variants as fallback. Older or unusual clients still get a compressed file, and you do not need special handling.
This is where gzip vs brotli turns from a debate into a plan. You send the smallest safe encoding for each user, and you pay heavy compression only once during build or warmup.
The Ups and Downs of Gzip and Brotli
Use this as a content aware choice, not a single switch. Precompress static files with Brotli to help your render path:
Conclusion
When you frame the choice, the answer is really a strategy. Precompress with Brotli for the assets that shape your render path. Compress dynamic content with the fastest safe option for your traffic.
Keep gzip as your universal safety net. Do that and your pages will feel lighter, your servers will stay calm, and your users will feel the difference.
FAQs
How do I enable Brotli or Gzip compression on my website?
On Nginx or Apache, enable the Brotli and Gzip modules, then set rules for text types like HTML and CSS. For static files, precompress during build and serve .br when the client sends br, with .gz as fallback. On Node servers, use middleware that negotiates Accept Encoding. If you use a CDN, turn on compression in its dashboard and let it cache your precompressed assets.
Is Brotli compression slower than Gzip for server processing?
Yes at high quality levels. Brotli spends more CPU time to squeeze extra bytes. For dynamic pages or APIs, start with Gzip at a mid level to protect Time to First Byte, or try Brotli at a low or mid level if you have headroom. For static assets, precompress with Brotli at the highest quality since that work happens once during build or cache warm.
What types of content benefit most from Brotli vs. Gzip?
You see the biggest wins on text. Use Brotli for HTML and CSS, and for JavaScript and JSON. SVG and web fonts also benefit. Images and video are already compressed, so avoid double compressing those. In short, use Brotli for cacheable text where smaller files speed paint, and use Gzip for live responses when server time matters most.
Can Gzip and Brotli be used together for optimal web performance?
Yes. Serve the best encoding each client accepts. Precompress static assets with Brotli and keep Gzip versions as fallback. Your server or CDN reads Accept Encoding and picks br when available, then falls back to gzip for older clients. This layered setup gives smaller files where it counts and universal support everywhere, without extra work for your build or deploy teams.
