How Do You Convert a JPG File to AVIF?

Why are you doing this conversion?

If you are reading this guide, your reason is probably clear: you run a website and images are weighing your pages down. Dozens of high-resolution JPGs, a gallery that loads slowly on a mobile connection, speed tests that keep pointing at image optimisation.

AVIF is one of the strongest solutions to that problem. At the same visual quality it generally produces significantly smaller files than JPG — the widely quoted roughly-half figure is an approximation and the actual gain varies from image to image.

But this conversion has a shadow side too, and half of this guide will be about it: compatibility.

Let's be clear about what the conversion actually does

Let's clear up one misconception at the outset: converting JPG to AVIF does not improve the image.

JPG is a lossy format. The file you have went through a compression pass the moment it was saved, and some of the information the eye does not notice was permanently discarded. If the image has block artefacts, banding in the sky or ringing around text edges, those are now the image's actual pixels.

AVIF takes that image and stores it more efficiently. In other words, what AVIF does is package a damaged image so that it takes up less space. It does not repair the damage.

Knowing this matters because it puts your expectations in the right place: what you gain is bandwidth and page speed, not quality.

Step-by-step conversion

1. Review the quality of your source

If you are starting with a JPG that has already been aggressively compressed and has visible artefacts, the result will be limited. If you have a cleaner source available — the original photograph, a PNG version, a raw file — converting from that always gives a better result.

That is not always possible, of course. If all you have is the JPG, carry on with it, but set your expectations accordingly.

2. Upload the files

Drag and drop your files onto our JPG to AVIF conversion tool. If you are working on site imagery you will probably be doing a batch upload; read the next step before you do.

3. Do not overdo the quality setting

The most common mistake here is trusting AVIF's efficiency and pulling the quality value way down.

Remember: your source has already been through one lossy compression. When you stack a second aggressive lossy compression on top, the artefacts feed each other. The block boundaries JPG left behind look like "real detail" to the AVIF encoder; the encoder either spends bits preserving them or blurs everything together. Neither is the result you want.

Start with a medium-high quality setting and compare the result against the source side by side. Because AVIF is efficient to begin with, your size gain will be substantial even at a reasonable quality value; sacrificing the image for the last few kilobytes is not worth it.

4. Check the result at full size

Small previews are misleading. Open the output at real viewing size, ideally alongside the original. Look particularly at these areas:

• Smooth gradients. Skies, gradient backgrounds. Is there banding?
• Fine texture. Hair, fabric, grass. Has it blurred into an oil-painting look?
• Text and sharp edges. If the image contains text, has legibility suffered?

If you see problems, raise the quality setting and try again.

5. Plan your JPG fallback

Do not skip this step. The responsible way to use AVIF on the web is to offer an alternative to visitors who cannot support it.

HTML's picture element exists for exactly this: you define multiple sources and the browser downloads the first one it can support. A browser that supports AVIF gets the AVIF, one that does not falls back to the JPG. The visitor notices nothing.

So do not delete your original JPGs — they are now your fallback layer.

Let's talk honestly about compatibility risk

Using AVIF on your web page is a reasonable decision. But putting an AVIF into circulation as a file is a different story.

Expect problems in these environments:

• Old devices and operating systems. Phones and computers that have gone a long time without updates cannot open the file.
• Desktop programs. Old Photoshop versions, classic viewers and most office software do not recognise AVIF.
• Email attachments. You cannot assume the recipient will be able to open it.
• Upload forms. Many e-commerce dashboards, classifieds sites and application systems do not accept AVIF.
• Social and messaging platforms. Some reject it, some accept it and convert it to their own format.

A simple rule: serve AVIF on a web page under your own control; when you need to send someone a file, send JPG.

Practical notes for batch conversion

If you are converting hundreds of images, watch out for a few things.

Try a small representative sample first. Pick five or ten images of different types — a photograph, a banner with text on it, a flat-colour graphic — and confirm that the quality setting you have chosen gives acceptable results across all of them. A single setting may not be ideal for every content type.

Factor in that AVIF encoding is computationally heavy. A large archive will take noticeably longer than saving as JPG. This is a one-off cost, but you need to plan for it.

Preserve filenames and do not disturb the original folder structure. If you are replacing site imagery, name matching can be critical.

In summary

Converting JPG to AVIF is a speed optimisation. It lets you deliver the same image with significantly less data, which makes a real difference for mobile visitors in particular. It does not add quality — the damage in the source stays exactly as it is. Do not push the quality setting too low, because stacking two layers of lossy compression degrades the result quickly. And most importantly: do not distribute AVIF on its own — keep your JPG fallback to hand.