I Cut My Site's Image Size in Half Without Changing a Single Photo
I was doing a performance audit on an e-commerce client's product catalog — 300+ JPG images. The site was slow, PageSpeed was in the 40s, and image payload was the top culprit. I didn't want to re-shoot anything or compromise visual quality. Converting the product JPGs to AVIF at quality 65 dropped the average file from 520KB to around 230KB. Visually identical. The site's Largest Contentful Paint dropped by over a second on mobile. That's the most impactful format switch I've made in recent memory.
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What AVIF actually is — and why it's better than just "newer than JPG"
AVIF is based on AV1, a video codec developed by a coalition of companies — Google, Apple, Microsoft, Netflix, Amazon — specifically to be royalty-free and better than everything before it. Video codecs are better at compressing images than image codecs because video engineers spent decades solving harder problems: how to compress 30 frames per second while keeping motion smooth. Still images are easier. AVIF applies that decades-of-video-research compression to single frames, which is why it beats JPG so decisively.
The e-commerce catalog conversion — what I actually did
The client had 300+ product photos from a professional photographer. All JPGs at high quality, averaging around 520KB each. Total image payload for the catalog section: about 160MB. The site was slow enough that users were abandoning category pages before the images loaded.
I ran a test batch of 30 images through AVIF conversion at quality 65 and compared them side-by-side with the originals on a monitor. I genuinely could not tell the difference at normal screen size. I had to zoom in to 200% and look at fabric texture before I could see any difference at all — and even then it was subtle. The AVIF files averaged 230KB. That's a 56% reduction.
After converting the full catalog, LCP on the category pages dropped from 4.1 seconds to 2.7 seconds on mobile. The client's conversion rate on those pages went up. That was the outcome from changing a file format.
What to know before committing to AVIF
I want to be straight about the tradeoffs I've encountered:
- Encoding is slow. AVIF is significantly more CPU-intensive to encode than JPG. For a large batch, expect it to take a while. On this site it runs server-side so your browser isn't stuck waiting, but a 300-image batch takes real time.
- Browser support is almost there, but not complete. Chrome (85+), Firefox (93+), Safari (16.4+), and Edge support AVIF. Older Safari and any Internet Explorer do not. If your analytics show a significant audience on older Safari, serve AVIF with a WebP or JPG fallback using the
<picture>element. - Email is a hard no. Email clients don't support AVIF. Use JPG for anything going into an email template.
- Not all CDNs handle AVIF yet. Check that your CDN will serve AVIF with the correct MIME type before deploying. Most major CDNs do now, but legacy setups might need configuration.
The re-encode consideration — when it matters and when it doesn't
Converting JPG to AVIF means re-encoding an already-lossy file. The AVIF encoder works from the pixels the JPG decoder produced — not from the original camera data. Any existing JPG artifacts carry forward into the AVIF output.
For product photos that were exported as high-quality JPGs from camera RAW, this is basically irrelevant — the artifacts at quality 90 JPG are invisible and don't affect the AVIF encoding meaningfully. For JPGs that have been through multiple rounds of editing and re-saving, the accumulated artifacts could show up more visibly in AVIF at aggressive compression settings. In that case, use a more conservative quality setting (70+) to avoid amplifying existing damage.
Files processed privately — deleted on completion
Your JPGs are uploaded over HTTPS and processed in temporary storage. Both the original and the generated AVIF are deleted automatically when the conversion finishes. No account needed, no retention.
Frequently Asked Questions
How much smaller will my AVIF be compared to the JPG?
Typically 40–60% smaller at equivalent visual quality. Product photos and natural photography see the biggest gains. Simple flat-color graphics see smaller gains.
Can I use AVIF in WordPress?
WordPress added native AVIF support in version 6.5. For older versions, plugins like Imagify or ShortPixel can serve AVIF with automatic fallbacks.
Is AVIF supported by Safari?
Safari added AVIF support in version 16.4 (released March 2023). All current iPhone and Mac users are on versions that support it, but serve a fallback for users on older OS versions.
What's the difference between AVIF and WebP for photos?
Both are better than JPG. AVIF generally achieves better compression than WebP for photographs, but WebP has broader legacy compatibility. Many teams serve AVIF to modern browsers and WebP as a fallback via the <picture> element.
Are my files stored after conversion?
No. Files are deleted automatically as soon as the conversion job completes.
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