JPEG, PNG, WebP and AVIF explained
Four formats cover almost everything, and each one wins in a specific situation. Here is which, and why.
Last updated: 2026-10-11
The comparison
| Format | Compression | Transparency | Best for | Watch out for |
|---|---|---|---|---|
| JPEG | Lossy, efficient | No | Photographs, maximum compatibility | Artefacts around sharp edges and text |
| PNG | Lossless, large files | Yes, full alpha | Screenshots, logos, flat graphics | Very large for photos |
| WebP | Lossy or lossless | Yes, full alpha | Almost everything on the modern web | Older software may not open it |
| AVIF | Lossy or lossless, very efficient | Yes, full alpha | Smallest files for web delivery | Slow to encode; support varies by browser |
JPEG: still the safe default
JPEG has been the standard for photographs for thirty years and remains the format that will open anywhere — every browser, every phone, every print shop, every piece of software from the last three decades. Its weakness is that it has no transparency and it blurs fine detail: text and hard edges pick up a faint halo.
Use JPEG when a photo needs to open everywhere and when the file will not contain sharp text or a transparency requirement.
PNG: for anything that is not a photograph
PNG stores every pixel exactly, which makes it ideal for screenshots, interface graphics, logos and diagrams — images with flat colour and crisp edges, where JPEG's blurring is obvious. It also supports full transparency, so a logo can have a clean cut-out background.
The cost is size. A photograph saved as PNG can be five to ten times larger than the same image saved as JPEG, because photographic detail is exactly what lossless compression cannot exploit. Screenshot as PNG: yes. Photo as PNG: usually a mistake.
WebP: the pragmatic modern choice
WebP supports both lossy and lossless compression, plus full transparency in both modes. In practice, a lossy WebP is typically 25–35% smaller than an equivalent-quality JPEG, and a transparent WebP is dramatically smaller than a transparent PNG of the same image.
It is supported by every current major browser. The only practical caution is interoperability with older desktop software and some publishing systems: if a client or a print workflow has to open the file directly, JPEG or PNG is safer.
AVIF: smallest files, most caveats
AVIF generally produces the smallest files of the four at comparable quality, which is why large sites use it. The catch is encoding: it is computationally expensive, so it is slow, and browser support — especially for encoding — varies. Some browsers can display AVIF but cannot produce it.
Because of that, this site only offers AVIF when your browser can genuinely encode it. A conversion that appears to succeed while silently producing a PNG would be worse than no option at all.
Transparency, and what it costs
If your image has transparent areas and you convert it to JPEG, those areas must become something. The convention is white. That is a deliberate, visible change: it is not a bug, and a tool that hides it behind a "success" message is lying to you. This site fills transparent areas with white when the target format cannot store transparency, and states it in the format description before you choose it.
If you need to keep transparency, choose PNG, WebP or AVIF. Of those, WebP is usually the best balance of size and compatibility.
EXIF orientation: the invisible trap
Phone cameras often store a photo in landscape orientation and record a rotation flag in the file's EXIF metadata, telling viewers "display this sideways". Most image software honours the flag; some ignores it, which is how photos end up mysteriously rotated after a round trip.
Two of those same files can therefore display differently depending on which tool opened them. This site applies the EXIF orientation during decoding, so the pixels it works on match what you actually see — and the output has no hidden rotation left to trip up the next program.
Formats with limits, and why
- GIF — animated GIFs would lose their animation, and static GIF has no advantage over PNG. Refused rather than silently flattened.
- SVG — a vector format with no fixed pixels, so it is only rendered at a size you choose on the SVG to PNG page. Other tools refuse it, because rasterising would discard the very thing that makes it useful.
- HEIC / HEIF — the format many iPhones shoot in, and one that most desktop browsers cannot decode natively. This site bundles a decoder, so theHEIC to JPG page converts it directly — no manual export first.
- TIFF — no browser image decoder supports it.
GIF and TIFF are shown as a clear rejection with the reason, on the file itself, at the moment you add it — rather than failing later or producing a damaged result. SVG and HEIC each have a dedicated page that explains how they are handled.
What to do in practice
- Photograph for the web? Convert to WebP at quality 0.80.
- Logo or graphic with transparency? WebP if compatibility allows, otherwise PNG.
- Screenshot? Keep it PNG.
- Something that must open in absolutely anything? JPEG.
- Chasing the last few kilobytes? Try AVIF, if the file is going straight to a web page.
Open the Bulk Image Converter to apply any of this to a whole folder at once.
Keep reading
- How to compress images without uploading them — What actually happens when a browser compresses an image, how to pick a quality level, and why a PNG will never shrink from a quality slider.
- Resizing images for the web: sizes, ratios and when to bother — How to choose real pixel dimensions, why the DPI field in your editor does not matter online, and the order in which to crop and resize.