When WebP came out, it replaced legacy JPEGs and PNGs on a lot of websites, because it made images smaller without hurting quality. But there's a newer open-source format called AVIF (AV1 Image File Format), and it promises even smaller files at the same visual quality. If you're aiming for a fast-loading site, picking between WebP and AVIF is not a small decision anymore.
Welcome back to BytebaseX. I'm Suptojit Modak, and in this guide, I'll compare AVIF vs WebP on file size, visual quality, browser support, and encoding speed, so you can decide if AVIF is ready for everyday use on your site. If you missed the previous post on image lazy loading, you can read it here.
What Is AVIF and How Is It Different from WebP?
WebP was built by Google and is based on the VP8 video codec. It supports lossy and lossless compression, transparency, and animation, and it makes files roughly 25% to 35% smaller than a regular JPEG at the same quality.
AVIF comes from the AV1 video codec, developed by the Alliance for Open Media, a group that includes Google, Apple, Netflix, Microsoft, and Mozilla. Because AV1 was built for video compression, it carries over some advanced techniques that work well on still images too. This is why AVIF usually beats WebP on file size, sometimes by a large margin, sometimes by only a little, depending on the image.
Compression and Visual Quality: How Much Smaller Is AVIF?
When you compress the same image to the same visual quality, AVIF usually wins on file size. But "usually" is doing some work here, because the gap changes a lot depending on what kind of image you're compressing.
- Photos and detailed images: this is where AVIF shows its biggest advantage. On photographs with lots of texture, like skin, foliage, or sky gradients, AVIF files can be 20% to 40% smaller than WebP at the same quality.
- Flat graphics and screenshots: on simpler images with large areas of solid color, like a marketing graphic or a UI screenshot, the gap between AVIF and WebP narrows. Sometimes it's only 10% to 15% smaller, and in a few cases the difference is barely noticeable.
- Color depth and HDR: AVIF supports 8-bit, 10-bit, and 12-bit color, along with HDR content. WebP is limited to 8-bit. If you're working with high dynamic range photography, this is a real advantage for AVIF, not just a spec sheet number.
- Lossless mode: this is one place where WebP can actually win. In lossless compression, WebP has beaten AVIF in independent tests on several image types, including photographs. So the rule "AVIF always wins" only really applies to lossy compression, not lossless.
AVIF vs WebP: Side-by-Side Comparison
| Feature | WebP | AVIF |
|---|---|---|
| File Size vs JPEG (lossy) | 25% to 35% smaller | 40% to 60% smaller |
| File Size vs WebP | Baseline | 10% to 40% smaller, depends on image |
| Color Depth | 8-bit | 8-bit, 10-bit, 12-bit (HDR support) |
| Encoding Speed | Fast, low CPU cost | Much slower, can be 10x to 47x slower than WebP |
| Decoding Speed (Browser) | Fast on all devices | Slightly slower, noticeable CPU spike on older phones |
| Global Browser Support (2026) | ~96% to 98% | ~93% to 95% |
Encoding Speed: Where AVIF Actually Costs You Something
This is the part most comparisons skip, and it matters more than people think if you're converting images at scale. WebP encodes fast. A typical 1080p image takes under 100 milliseconds to convert to WebP, using very little CPU power.
AVIF is a different story. Depending on the settings you use, converting the same image to AVIF can take anywhere from one second to several seconds, and at maximum quality settings it can stretch to 30 or even 40 seconds for a single image. Independent benchmarks have measured AVIF encoding at 10 to 47 times slower than WebP for comparable quality, along with much higher memory use during the conversion.
Why does this matter for you? If you're converting a handful of images by hand using a tool like Squoosh, the difference is barely noticeable, maybe a few seconds either way. But if you run a site that converts images automatically at upload time, or a CMS plugin that batch-converts your whole media library, this encoding cost adds up fast and can genuinely slow down your workflow or spike your server load if many images convert at once.
There's a practical middle ground here. Most AVIF encoders let you set an "effort" level. Lower effort settings encode much faster with only a small loss in compression efficiency, so you don't need to use the slowest, most thorough setting to get most of AVIF's benefit.
Decoding Speed: What Happens on the Visitor's Device
Encoding happens once, on your server or your computer. Decoding happens every single time a visitor loads your page, so this side of the equation matters just as much, maybe more.
On modern phones and laptops, decoding an AVIF image is fast enough that visitors won't notice any delay. On older or budget Android devices, though, independent testing has found a measurable CPU spike, in the range of 5% to 10% compared to decoding a JPEG or WebP file of the same image. For a single image this is nothing. For a page with dozens of AVIF images, this can add up to a small but real rendering delay on lower-end hardware.
This doesn't mean AVIF is unsafe to use. It means the file size savings you get from AVIF usually outweigh this small decoding cost, especially for visitors on slower mobile networks where downloading less data matters more than a few extra milliseconds of decode time. But it's not the free win some guides make it sound like.
Browser Support: Is There Still a Real Gap?
Both WebP and AVIF are supported by every major browser you'd expect: Chrome, Firefox, Safari, and Edge all handle both formats natively as of 2026. But "supported by every major browser" and "100% global support" are two different claims, and the second one isn't accurate for either format.
WebP sits at roughly 96% to 98% global support, counting every browser and device actually in use. AVIF is a bit behind, at roughly 93% to 95%. The gap for AVIF comes almost entirely from one place: Safari didn't add AVIF support until version 16.4, released in 2023. Any iPhone or iPad still running iOS 15 or older, mostly devices from 2018 or earlier, can't decode AVIF at all. WebP doesn't have this problem, since Safari added WebP support years earlier.
For most websites, this gap is small enough that it doesn't change the decision. But if your analytics show a meaningful chunk of visitors on very old iPhones, or if your audience skews toward corporate or government devices that are often a few years behind on updates, it's worth checking your own numbers before assuming AVIF works for everyone.
Is AVIF Ready for Everyday Use?
Based on everything above, yes, with one small addition. AVIF is production-ready for most websites in 2026. The file size savings are real, the visual quality holds up, and the remaining browser gap is small and easy to cover.
The safest way to use AVIF is to offer it as your first choice while keeping WebP as a fallback, so the small percentage of unsupported browsers still get a fast, modern image instead of falling all the way back to a heavy JPEG. The <picture> element handles this automatically, letting the browser pick the best format it understands:
<picture>
<source srcset="banner.avif" type="image/avif">
<source srcset="banner.webp" type="image/webp">
<img src="banner.jpg" alt="Optimized promotional banner" width="1200" height="630" loading="lazy">
</picture>This is worth the small extra setup mainly for image-heavy sites, photography portfolios, product catalogs, or any page where hero images carry a lot of the page weight. If you run a simple blog with a handful of screenshots per post, sticking with WebP alone is still a perfectly reasonable choice, and it saves you the encoding overhead on the backend.
Conclusion
AVIF wins on file size in most real-world cases, sometimes by a wide margin on photos, sometimes by a small margin on flat graphics, and occasionally not at all in lossless mode. That advantage comes with a real cost on the encoding side, and a small but measurable cost on older devices during decoding. Neither of those costs is a reason to avoid AVIF outright, but they are reasons to be honest about the trade-off instead of treating AVIF as a free upgrade over WebP.
For most sites, the practical answer is to use both: AVIF first for the compression gain, WebP as the safety net for the small slice of devices and use cases where AVIF doesn't fit. This guide is the sixth post in the Image Optimization series on BytebaseX. In the next post, I'll compare SVG vs PNG vs JPEG to work out exactly when a vector format beats a raster one.
