Image format conversion is one of those tasks that sounds simple but has a surprising number of ways to go wrong — quality loss from the wrong compression settings, formats that don't survive the conversion cleanly, tools that add watermarks or require accounts for basic operations. Portimg is a browser-based image converter that handles the common conversions without those complications.
This is a practical overview of what it supports and when each format choice makes sense.
What it converts
The converter handles the formats you're most likely to need: JPG, PNG, WebP, AVIF, and GIF. The conversions go in both directions between most of these — JPG to PNG, PNG to JPG, WebP to JPG, JPG to WebP, PNG to AVIF, WebP to AVIF, and so on. GIF converts to static PNG or JPG, which extracts a single frame rather than preserving animation.
For the full current list of supported conversions, the raster-to-raster converter shows available output options once you upload a file in a given format.
Which format to convert to
The right output depends on where the image is going and what it needs to do there.
JPG is the most universally compatible format — everything opens it. Choose it when compatibility with unknown software or platforms is the priority, or when you're sharing with someone whose setup you don't control.
PNG is lossless and supports transparency. Choose it when you need to preserve exact pixel quality, maintain a transparent background, or work with logos and graphics that will be composited over other elements.
WebP produces smaller files than JPG at comparable quality and supports transparency like PNG. It's the best default for web use — all major browsers support it, and the file size reduction translates directly to faster page loads. If images are going onto a website, WebP is usually the right format.
AVIF achieves better compression than WebP but has narrower support across older software and systems. It's well suited for web contexts where you've confirmed support, but JPG or WebP is safer when you're unsure.
Using the tool
Go to portimg.com, navigate to the converter, upload your image or images, select the output format, and download the result. Multiple files are packaged as a ZIP. No account is required, and files are deleted from the server after processing. It works the same way on mobile, tablet, and desktop — any device with a modern browser.
Quality considerations
A few format-specific things worth knowing before converting:
Converting from PNG (lossless) to JPG (lossy) involves a quality trade-off that's permanent. The visible difference is usually small at reasonable compression settings, but it can't be undone — keep originals if there's any chance you'll need them again.
Converting from JPG to PNG doesn't improve quality. PNG will store the current pixel values without further loss, but the quality loss from the original JPG compression has already happened. The file gets larger without getting better. This conversion only makes sense when you specifically need PNG — for transparency support or a platform requirement.
Converting WebP or AVIF to JPG applies a second round of lossy compression on top of the first. The result is usually fine for everyday use, but professionals working with images where quality matters should convert from original uncompressed sources rather than from already-compressed web formats.