WebP, AVIF, JPEG or PNG — which should you use?
Most format advice is a table of file sizes. That is the least useful part. The formats differ in what they can represent at all — and once you know that, the size question answers itself.
Lossy or lossless, transparent or not — that is the whole decision
JPEG is lossy and has no transparency at all. It was built for photographs and it is still excellent at them, but it cannot represent a transparent pixel — the concept does not exist in the format.
PNG is lossless and does have transparency. Nothing is thrown away, which is why it is the right choice for screenshots, logos, diagrams and anything with text or hard edges — and why it is a poor choice for a photograph, where "throw nothing away" means a very large file.
WebP and AVIF are the modern pair, and they removed the trade-off: both support lossy compression AND transparency. That combination is genuinely new. Before them, a transparent image had to be stored losslessly, which is why so many oversized PNGs exist on the web.
So: photograph → a lossy format. Flat graphic or text → lossless, or lossy at high quality. Needs transparency → anything except JPEG.
The conversion you should never make
Transparent PNG to JPEG. JPEG has no alpha channel, so the transparency has to go somewhere — and every tool that performs this conversion silently composites your image onto a background colour it picked. Usually white, sometimes black. The result looks fine on a white page and catastrophic anywhere else, and there is no undo: the transparency is not hidden, it is gone.
Our converter refuses. If your image carries transparency and you ask for JPEG, it keeps a format that can represent it and tells you what it did. If you genuinely want a flattened image on a specific background, that is a compositing decision and it belongs in an editor where you choose the colour.
The other conversion worth thinking twice about is lossy to lossy — JPEG to WebP, WebP to AVIF. It works and is often worth it, but you are re-encoding something that was already encoded, so a little quality goes each time. Convert from the best original you have rather than from a copy of a copy.
Is it safe to use WebP and AVIF yet?
For the web, yes. WebP works in every browser people actually use and has for years. AVIF is supported by all current major browsers too; the practical cost is encoding time, not compatibility.
Outside the browser it is less uniform. Some older desktop software, a few printers and the occasional upload form still expect JPEG or PNG. If a file is going somewhere you do not control — a print shop, a government portal, a client who will open it in something ancient — send JPEG or PNG and keep the modern format for your own site.
A reasonable habit: keep your originals in a lossless format, convert to WebP or AVIF for publishing, and convert to JPEG only when something on the far end demands it.
Frequently asked questions
Is WebP or AVIF safe to use on a website now?
Yes for both, in every current browser. The remaining caution is outside the browser: some older desktop applications, printers and internal systems still only understand JPEG and PNG. If the image is going into a website, use WebP or AVIF; if it is going to a person who will open it in an unknown program, JPEG is the safer handoff.
Can converting a JPEG to PNG restore its quality?
No, and it is the one conversion worth avoiding. Whatever a JPEG threw away is gone; PNG will then store those exact damaged pixels losslessly, producing a file several times larger with no improvement at all. Convert to PNG only when you need transparency or a lossless master from a lossless source.
Does converting reduce quality?
Converting to a lossy format re-encodes, so a small amount is given up — controlled by the quality preset you pick, from 92 down to 68. Converting between lossless formats gives up nothing. The practical rule is to convert from your best original rather than from a copy that has already been through a lossy encode.
Which format is best for a logo or a screenshot?
Anything with hard edges and text wants a lossless or high-quality encode — PNG is the traditional answer and still a good one, and lossless WebP is usually smaller for the same result. Avoid JPEG here: its compression produces visible fringing exactly along the sharp edges these images are made of.
Can I convert several images at once?
Yes — up to 20 files per job, each up to 100 MB, all converted to the format you choose. Unlike the compressor, the converter always converts: it will not quietly hand back your original because the new file came out larger, since a converter that declined to convert would be broken.