Image Format Converter

It depends on what the picture is made of, not on which format is better. PNG stores every pixel exactly and compresses by finding repetition, so it suits flat colour, screenshots, diagrams, logos and anything carrying text or hard edges — a JPEG of a screenshot smears the letters. JPEG discards detail the eye is poor at noticing, which works on photographs, where there is little flat colour to repeat and a PNG of the same photo can run several times larger. The awkward case is a photograph with text over it, and there the file size usually decides.

On the web, yes — every current browser reads WebP, and it generally gives a smaller file than PNG or JPEG at the same visible quality, which makes it a sensible default for a page you control. Away from the browser it is patchier. Older desktop software, some print and photo-lab upload forms, a few email clients and plenty of corporate document systems still refuse a .webp, and whoever you send one to may find it will not open. If the image is going to a person rather than a web page, send PNG or JPEG.

Converting to PNG does not: the pixels arrive intact, which is also why the file often grows, since none of the detail an earlier JPEG threw away comes back to justify the extra weight. Converting to JPEG or WebP re-encodes, so each pass costs a little, and the loss compounds — convert, then convert again, and you are encoding an encoding, with the artefacts of the first round preserved faithfully by the second. Where you still have the original, convert from that rather than from a copy that has already been round the loop twice.

An alpha channel only survives into a format that has one, which here means PNG and WebP. JPEG has none, so transparent areas have to become something solid, and what colour they become is decided by the encoder rather than by you. If the background matters, convert to WebP and the transparency comes through. If the destination insists on JPEG, the PNG to JPG tool is the better route: it offers a colour picker and fills the transparent areas with the colour you name, so you get a deliberate background instead of an accidental one.

The slider runs from 0 to 1 and starts at 0.92, near the end of the range where extra quality still costs real bytes without showing much. For photographs, somewhere around 0.8 is the usual compromise: the difference is hard to see and the file is noticeably lighter. Below roughly 0.6, blockiness around text and hard edges becomes obvious. The bottom of the range is genuinely reachable, and dragging it to 0 once is instructive. The slider does nothing for PNG, which is why it disappears when you select that format.

No. The file is opened through a blob URL that exists only inside the tab, and decoding and re-encoding happen on a canvas on your own machine — the component makes no network call at any point, so there is nothing to upload and no queue to sit in. Each blob is released as soon as you replace the image or leave the page. Two consequences follow: the tool keeps working if your connection drops after the page has loaded, and the ceiling on file size is your device's memory rather than an upload limit somebody else set.

Yes, all of it. The mechanism is a redraw — the browser decodes the picture, paints it onto a canvas and encodes what is on the canvas, and a canvas holds pixels and nothing besides. Capture date, camera and lens, exposure settings, GPS coordinates, copyright fields and any embedded thumbnail are missing from what you download. That is welcome when you are about to post a photograph taken at home, and a nuisance when you are converting an archive and the dates were the point. Where metadata matters, keep the original beside the converted copy.

Photos from an iPhone are usually HEIC, and most browsers cannot decode one at all, so no preview appears and the message reads: Unable to load image file. Nothing is wrong with the photo. The HEIC to JPG converter here deals with that format specifically, so run it first and convert its result if you need PNG or WebP. You can also head the problem off at source — on iOS, Settings, Camera, Formats, Most Compatible makes the camera shoot JPEG, and sharing or emailing a photo often converts it on the way out anyway.