Convert PNG to JPG

The transparency problem

This is the single thing that goes wrong when people convert PNG to JPEG, and it is not really a bug: JPEG has no alpha channel. It physically cannot store "this pixel is see-through". So every transparent pixel must become some opaque colour during conversion, and the value it gets is whatever the canvas underneath happened to contain — which, for most converters, is black. That is why a logo with a transparent background so often comes back looking like it was cut out of a dark rectangle.

The fix is to decide the colour deliberately rather than inherit it. Pick the background your image will actually sit on: white for most documents and pages, black for dark interfaces, or a custom colour to match a specific brand or slide background. If nothing you pick looks right, that is a sign the image should not be a JPEG at all — convert it to WebP instead, which carries transparency and is supported by every current browser.

Which format for which image

• Photographs — JPEG or WebP. Both are lossy, which is exactly right for continuous-tone images where fine noise carries no meaning. WebP will usually be 25–35% smaller at matching quality.
• Screenshots, logos, diagrams, anything with text — PNG or WebP. JPEG works by discarding high-frequency detail, and a sharp edge is high-frequency detail, so lettering picks up a visible halo of fringing.
• Anything needing transparency — PNG or WebP. Never JPEG, for the reason above.
• When in doubt — WebP. It handles both photographic and flat-colour content well, supports transparency, and is smaller than either alternative.

Converting the other way

JPEG to PNG comes up often and is usually not worth doing. PNG is lossless, but lossless does not mean restorative — converting a JPEG produces a perfect, considerably larger copy of an image whose detail is already gone, artefacts faithfully preserved. Expect the file to grow several times over with nothing visible to show for it. The legitimate reasons are needing transparency support before editing, or feeding a tool that refuses JPEG input.

The same caution applies to repeated conversion in general. Each lossy encode preserves the previous encoder's artefacts and adds its own, so quality degrades in steps that compound. Always convert from the original file if you still have it, rather than from something that has already been through the process once.

What conversion removes

Because the image is redrawn onto a canvas and re-encoded, all metadata is dropped: camera and lens details, exposure settings, capture timestamps, and any GPS coordinates the camera embedded. That is a privacy benefit when you are about to publish a photo taken somewhere you would rather not disclose, and a genuine loss if you were relying on that information. Keep the original either way.

Need a smaller file at the same dimensions? The compressor does that. Need different dimensions? The resizer handles it, and the favicon page produces the specific sizes a site icon needs.

Common questions

Why did my transparent background turn black?

Because JPEG has no alpha channel — it cannot store transparency at all, so every see-through pixel has to become some solid colour on the way in. Most converters never ask and end up writing black, which is what an empty canvas contains before anything is drawn on it. This page asks instead: pick the background colour before converting, defaulting to white because that is what the majority of pages and documents sit on. If keeping the transparency matters more than the format, convert to WebP, which is the only option here that is both widely supported and capable of carrying alpha.

Should I convert PNG to JPEG at all?

It depends entirely on what the image contains. A photograph stored as PNG is usually several times larger than it needs to be, and converting to JPEG or WebP is a straightforward win — PNG is lossless, so it faithfully stores photographic noise that nobody will ever miss. Screenshots, logos, diagrams, and anything with text or hard edges are the opposite case: JPEG's compression works by discarding high-frequency detail, which is exactly what a sharp edge is, so it produces visible fringing around lettering. Keep those as PNG, or use WebP, which handles both kinds well.

Is converting JPEG to PNG worth doing?

Rarely, and it is worth being clear about why. PNG is lossless, but converting from JPEG cannot undo compression that has already happened — you get a perfect, much larger copy of an image that already lost detail, artefacts included. The file typically grows several times over for no visible gain. The genuine reasons to do it are needing a format that supports transparency before you edit the image, or feeding a tool that will not accept JPEG. Otherwise, keep the JPEG.

What does quality 85 actually mean?

It is a dial on how aggressively the encoder discards detail, not a percentage of anything. Between 100 and roughly 85 you shed a great deal of file size and almost no visible quality; from 85 down to about 60 the losses become noticeable on close inspection, particularly around text and sharp edges; below 60 the blocky artefacts are obvious. 85 is a good default for photographs. The number is not comparable across formats — WebP at 85 and JPEG at 85 are different encoders making different trade-offs, and WebP will generally produce the smaller file.

Does converting lose image quality?

Converting to JPEG or WebP does, because both are lossy formats — and re-encoding an image that was already lossy compounds it, since the second encoder faithfully preserves the first one's artefacts and then adds its own. Convert from the original whenever you still have it rather than from a copy that has already been through this once. Converting to PNG loses nothing further, but it also recovers nothing that was already gone.

Is my image uploaded anywhere?

No. Decoding, flattening, and re-encoding all happen in your browser using canvas, and the file never leaves your device. Nothing is sent to a server or stored, and the page keeps working with the network disconnected once it has loaded.