Free Online Image Converter – Convert PNG, JPG, WebP, HEIC & More

Choosing a Format Is Choosing What to Lose

Every image format makes a trade between file size, visual fidelity and features. There is no best one — there is a best one for a particular image and a particular use, and the differences are large enough to matter.

The distinction that decides most conversions is lossy versus lossless. Lossy formats permanently discard image data that the eye is unlikely to notice, which is how a photograph shrinks dramatically with no visible change. Lossless formats keep everything, so they reproduce the original exactly and stay much larger.

Why a Photo in PNG Is Enormous

Lossless compression finds repetition. A screenshot of a document is mostly identical white pixels with sharp black shapes, which compresses brilliantly. A photograph has almost no exact repetition — every patch of sky is subtly different — so there is little for the algorithm to find, and the file stays close to its raw size.

This is why the same picture saved as PNG can be several times the size of the JPG version at no visible advantage. It is also why the reverse mistake is worse: a logo or screenshot saved as JPG develops faint smudging around every sharp edge, because lossy compression handles hard transitions badly. Those artefacts are permanent.

Converting Lossy to Lossy Loses Twice

Each save to a lossy format discards data, and the loss compounds because the second compression is applied to an image that already carries the first one's artefacts.

Converting JPG to WebP, then back to JPG, then to WebP again produces visible degradation even though every individual step looked fine. Keep an original in a lossless format and generate lossy versions from it each time, rather than converting a converted file.

Converting lossy to lossless does not recover anything. A JPG saved as PNG produces a much larger file containing exactly the same visible damage, since the discarded data is gone rather than hidden.

Transparency Survives Only Some Conversions

JPG has no concept of transparency. Converting a logo with a transparent background to JPG fills that background with something — usually white or black — and once flattened it cannot be restored.

The symptom is a logo that looks correct on a white page and appears in a white box the moment it is placed on a coloured one. If your image has transparency and you need it, PNG and WebP preserve it and JPG does not.

When to Convert, and When Not To

• Photographs for the web — WebP first, JPG as a fallback where compatibility matters. Both are good at photographic content and WebP is generally smaller.
• Logos and icons — PNG or WebP for transparency and crisp edges. Never JPG.
• Screenshots — PNG or lossless WebP. Text becomes unpleasant to read after lossy compression.
• Anything you will edit again — keep the original untouched and convert copies. The original is the only thing that still has all the data.
• Images already the right format and size — leave them. Re-saving a JPG at the same settings still loses a little for no benefit.

Format, Size and Dimensions Are Three Separate Things

These get conflated constantly, and each is a different tool.

Converting changes the encoding — how the pixels are stored. Compressing changes the quality setting within a format, using our image compressor. Resizing changes the pixel dimensions, which is what the image resizer does.

When a file is too large, the order that works is usually resize first, then choose the right format, then compress if it is still too big. Resizing a 4000-pixel-wide photo down to the 1200 pixels it will actually display at removes most of the file size before any quality trade-off is needed at all.

Conversion Happens in Your Browser

This tool converts images locally rather than uploading them to a server, which matters for anything you would not want to send to a third party — documents containing personal information, unpublished work, or client material under confidentiality.

One consequence worth knowing: converted images do not retain camera metadata such as GPS coordinates and device details. That is usually an advantage, since location data embedded in a photo is a common and unintended disclosure, but if you need that information preserved you should keep the original file.