Image formats solve different problems, which is why files so often arrive in one you can't use: an iPhone photo that Windows won't open, a WebP that an upload form rejects, a scanned TIFF too large to email. These converters handle the common cases in both directions, and all of them run inside your browser — the file never leaves your device.
Choosing the format you convert to
| Format | Compression | Transparency | Best for |
|---|---|---|---|
| JPG | Lossy | No | Photos that must open everywhere |
| PNG | Lossless | Yes | Screenshots, logos, graphics with sharp edges |
| WebP | Lossy or lossless | Yes | Websites — usually smaller than JPG or PNG |
| AVIF | Lossy or lossless | Yes | The smallest files for websites, slower to create |
A simple rule covers most cases: JPG when someone else's system has to accept the file, PNG when every pixel or a transparent background matters, and WebP or AVIF when it is going on a website you control.
Formats you usually convert from
HEIC is the default camera format on iPhones. It is efficient, but many Windows apps, websites and upload forms still can't open it, so converting to JPG is the quickest fix; convert to PNG instead when the image has transparent areas or you will keep editing it (a photo comes out about four times larger than the JPG). TIFF comes from scanners, print workflows and archives: large, lossless and often multi-page — the TIFF converters here export every page, not just the first. Going the other way, PNG to TIFF keeps transparency and 16-bit colour exactly, which a converter that goes through the browser's canvas can't: on our soft-shadow test image, 90% of the partly transparent pixels changed colour that way. GIF is mostly used for short animations; converting one to JPG or PNG keeps its first frame as a still image. Going to GIF is the harder direction for transparent images: a GIF pixel is fully clear or fully solid, so PNG to GIF blends a logo's soft edges into the colour it will sit on (on our test logo the edge error fell from 45 to 2 on white) and keeps the colours of a simple graphic exactly. SVG is a vector format, so turning it into PNG means choosing the exact pixel size you need; the other way, PNG to SVG traces a logo or drawing into real vector shapes rather than wrapping the pixels in an SVG file.
Two details converters often get wrong
Converting a transparent image to JPG forces every transparent pixel to become a solid colour, because JPG has no alpha channel. Here you choose that colour instead of silently getting black. And browsers can display AVIF but cannot create it on their own, so the AVIF tools load an open-source encoder the first time you use them rather than handing back a PNG with the wrong name.
The other direction has its own trap. Many AVIFs saved from the web use Display P3, a wider colour range than sRGB, and a converter that draws them as sRGB pulls in the most vivid colours: in our test the reddest red shifted by 6.8 Delta E. The AVIF to JPG and AVIF to PNG tools keep those colours and say when a file was transparent, animated or HDR. And a .jfif file is already a JPEG, so JFIF to JPG hands it back byte for byte instead of compressing it a second time.
What a conversion cannot undo
Converting a file changes its container, not its history. A JPEG that has already lost detail does not get it back by becoming a PNG — the PNG simply stores the damaged pixels losslessly, in a much bigger file: in our test a 1.31 MB phone photo became a 5.8 MB PNG with JPG to PNG, and 7.6 MB when the browser's own PNG encoder wrote it with an empty transparency channel. A flat graphic shrank instead, from 34 KB to 9 KB. Going the other way, from PNG to JPEG, discards transparency and adds compression artefacts that cannot be removed afterwards.
The practical rules that follow:
- Never convert your only copy. Keep the original and convert a duplicate.
- Converting to JPEG drops things silently: transparency becomes a solid colour, animation becomes one frame, and metadata is usually stripped.
- Lossy to lossy is two rounds of damage. JPEG → WebP is fine for publishing, wrong for archiving.
- Screenshots and logos belong in PNG. JPEG spends its bytes on exactly the hard edges those images are made of, and often produces a larger, worse file.
How much smaller are the modern formats, really?
The same photograph at 2048 px wide, encoded three ways on the same machine: JPEG at quality 80 came to 734 KB, WebP at quality 80 to 626 KB (−15%), and AVIF to 583 KB (−21%). Useful, but a long way from the “half the size” that gets quoted — those figures come from flat graphics and illustrations, not detailed photographs.
There is also a quirk worth knowing before you plan around AVIF: every current browser can display it, but none of them can create one. Browser-based AVIF converters, including ours, ship a WebAssembly encoder of their own, which is why the first conversion on the page takes a moment. The full comparison is in which image format to use.
Private by design
Decoding and re-encoding both happen on your own device. Nothing is uploaded, there is no account, and there is no limit on file size or on how many files you convert.