PNG or JPG: choosing the right format
The choice comes down to two questions: does the image need transparency, and does it contain text, lines or flat colour? Everything else follows from those.
PNG and JPG are the two formats almost every tool can read, and picking between them is a decision people second-guess constantly. The reasoning is short once you separate what the formats are good at.
PNG: lossless, with transparency
PNG stores every pixel exactly. Save a PNG, open it, save it again, and the pixels are still the same. It also carries an alpha channel, so partial transparency works properly: a soft shadow can fade out smoothly rather than being either solid or gone.
The cost is file size. For a photograph, PNG is typically several times larger than a JPG of the same image. The format is designed for images with large areas of identical colour, where its compression works well.
JPG: lossy, compact, no transparency
JPG throws away detail it judges hard to see, mostly fine colour variation, and stores the rest compactly. For photographs this is an excellent trade. For anything with sharp edges and flat colour it is a poor one: text picks up fringing, flat backgrounds develop mottling, and repeated saves accumulate visible damage.
JPG also has no alpha channel. The format predates widespread transparency support, and no amount of quality adjustment changes that. Transparent pixels have to be replaced by a solid colour.
A practical rule
| Image | Use | Why |
|---|---|---|
| Screenshot, diagram, chart | PNG | Sharp edges and flat colour are exactly what PNG compresses well, and text stays crisp. |
| Logo, icon | PNG | Usually needs transparency, and often gets scaled, so it should stay lossless. |
| Photograph | JPG | Continuous tone hides the loss, and the size saving is large. |
| Photo with a cut-out subject | PNG or WebP | Needs alpha, so JPG is out. WebP is smaller if the destination supports it. |
| Scanned document | PNG | Text quality matters and the page count is small enough that size is tolerable. |
Two mistakes worth avoiding
Converting a JPG to PNG to "improve" it does not work. The detail JPG discarded is gone, and re-saving it as PNG only preserves the damage losslessly. If you need a better version, you need to go back to the original source.
Lowering the JPG quality repeatedly is worse than lowering it once. Each save is another round of loss. Decide the quality when you first export, and keep the lossless original.
Convert an image now
The converter reads PNG, JPG, GIF, BMP, TIFF, ICO, WebP, AVIF, HEIC and SVG, and writes PNG, JPG, WebP, GIF, BMP, TIFF, ICO, AVIF and PDF. It states for each file whether the work happened on your device or on the server.
Converters mentioned in this guide
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Resizing images without wrecking them
Resizing changes an image more than most people expect. Here is what the three fit modes do, why enlarging is a losing game, and how to choose target dimensions.