In 2025, serving legacy JPEGs to your users is like mailing them a VHS tape. It works, but it's inefficient, heavy, and outdated.
The web has moved on. First came WebP, Google's champion that promised (and delivered) 30% savings. Now, AVIF is the new challenger, claiming even tighter compression at similar quality.
But claims are cheap. As a developer, I don't trust marketing pages; I trust data.
So, for this benchmark, I didn't just read the spec sheets. I took 50 high-resolution source images (a mix of complex photography, flat illustrations, and screenshots) and ran them through the ringer using BulkResizeImages.online and other command-line tools.
Here is the definitive answer to the question: What is the best image format for the web in 2025?
The Verdict (TL;DR)
If you only have 30 seconds, here is what you need to know:
- Best Overall (The Winner): WebP. It is supported by >97% of browsers, offers excellent compression, and decodes quickly. It is the safe, "set it and forget it" default for 99% of web projects.
- Best for Maximum Compression: AVIF. It is typically 15-20% smaller than even WebP. However, it takes longer to compress (encode) and has slightly less universal support on older devices.
- The Loser: JPEG. Unless you strictly support Internet Explorer 11 (why?), there is no technical reason to serve JPEGs as your primary format anymore.
Round 1: File Size Benchmark
We took a standard 1920x1080 photograph (a complex street scene with lots of color and detail). The original PNG master file was 3.2 MB.
We compressed it to a matching "Visual Quality" level (roughly equivalent to JPEG quality 80).
| Format | Final File Size | Reduction vs. Original | Reduction vs. JPEG | | :--- | :--- | :--- | :--- | | Original PNG | 3.2 MB | 0% | - | | JPEG | 245 KB | 92% | 0% | | WebP | 156 KB | 95% | -36% | | AVIF | 112 KB | 96% | -54% |
Analysis
The data doesn't lie. AVIF is less than half the size of the equivalent JPEG.
Imagine you are running an e-commerce store with 100 images on a collection page.
- With JPEGs to load: ~25 MB total payload.
- With AVIF to load: ~11 MB total payload.
That is the difference between a user staying and a user bouncing because the page was "too slow."
Round 2: Visual Quality at Low Bitrates
File size isn't everything. If the image looks like a blocky mess, the savings aren't worth it. This is where "Generation Loss" comes in.
We pushed the formats hard, asking for a target file size of just 25 KB for a 800px wide image.
- JPEG: Completely fell apart. Massive "blocking" artifacts (square grids) appeared in the sky and flat colors. Text became unreadable.
- WebP: Held up reasonably well. Some slight blurring on sharp edges, but no blocking artifacts. Colors remained accurate.
- AVIF: Incredible. It preserved texture detail that WebP blurred out. It looked almost identical to the 50KB version.
Winner: AVIF. Its compression algorithm (derived from the AV1 video codec) is incredibly smart at discarding data your eye doesn't notice, rather than just crunching pixels into blocks.
Round 3: Browser Support & Compatibility
This is where the rubber meets the road. A tiny file is useless if your user's iPhone can't open it.
- JPEG: 100% support. (Obviously)
- WebP: ~97-98% support. Works on everything modern. Even Safari (the long-time holdout) has supported it for years now.
- AVIF: ~93% support. It works on all modern Chrome, Firefox, and Safari versions. However, it relies on newer OS updates. An older Android phone or an iPhone stuck on an old iOS version might struggle.
The Recommendation
For 2025, the strategy is simple: WebP is the new baseline.
Support is high enough that you often don't even need a JPEG fallback for general audiences. If you are building a cutting-edge portfolio site, use AVIF. For everyone else, WebP is the sweet spot.
How to Check This Yourself
You don't need a lab to see these results.
- Open BulkResizeImages.online.
- Drag in your heaviest banner image.
- Set the format to JPEG and Quality to 80. Note the size.
- Switch format to WebP and Quality to 80. Note the size.
You will consistently see that 30-40% drop in file size.
Conclusion
The format war is largely over, and JPEG lost.
- Stop exporting JPEGs from Photoshop.
- Start defaulting to WebP for all your website images.
- Experiment with AVIF if you are a performance obsessive.
Your server bandwidth will thank you, and your users—especially those on mobile connections—will thank you even more.
