Image Converter

What goes in and what comes out

Five input types are accepted: PNG, JPEG, WebP, GIF and BMP. Three output types are offered: PNG, JPEG and WebP. Each file is decoded by the browser, painted onto an off-screen canvas at its exact original width and height, then re-encoded in the format you picked. Nothing is scaled, so a 3000 x 2000 input gives a 3000 x 2000 output.

The original name is kept and only the extension changes, so holiday-01.png becomes holiday-01.webp. Everything runs in your browser, so your files never leave your device.

Picking the right target format

PNG is lossless and keeps an alpha channel. It is the right answer for screenshots, logos, line drawings, charts and anything with flat blocks of colour or transparency. It is the wrong answer for photographs, where the file can balloon well past the JPEG you started from.

JPEG is lossy, has no transparency and is understood by every piece of software ever written. Choose it for camera photos, for anything you are attaching to an email, and for upload forms that only list .jpg and .jpeg.

WebP is lossy at these settings and supports transparency, which is the one thing JPEG cannot do. For the same visual quality it usually writes a smaller file than JPEG, though the margin varies a lot depending on the picture. Every current browser displays it, but some older desktop software and a few upload forms still refuse it, so keep a JPEG copy if the file is going to a third party.

One thing to be clear about: converting a JPEG to PNG cannot bring back detail the JPEG compression already discarded. You get a lossless copy of a lossy image, in a larger file. Converting JPEG to JPEG re-encodes it and throws away a little more.

The quality slider

Quality is adjustable anywhere between 0.10 and 1.00, and starts at 0.92. It is passed straight to the encoder for JPEG and WebP and is ignored entirely for PNG, which has no quality dial. Around 0.90 most people cannot see the difference from the original at normal viewing size. Below about 0.60, flat areas such as sky start showing blocky patches and text edges pick up a halo. Pushing all the way to 1.00 adds a lot of bytes for very little visible gain, so 0.85 to 0.92 is the practical band.

When the target is JPEG, the canvas is painted white before the image is drawn. Transparent pixels therefore come out white, not black, which is what you want for most logos on light pages and wrong if your artwork was designed for a dark background.

Batches, the zip, and where it strains

Drop a whole folder's worth of files. Anything with an unsupported type is skipped with a note and the rest continue. With exactly one file in the list you get a direct download. With two or more, all outputs are bundled into converted-images.zip.

That archive is built locally with fflate at compression level 6, but do not expect it to shrink anything: PNG, JPEG and WebP are already compressed, so the zip lands close to the sum of its parts. It exists to save you fifty separate download prompts, not to save space.

Two limits worth knowing. First, every converted file is held in memory until the zip is written, so a hundred large images at once can exhaust a phone browser's memory budget. Batches of twenty or so are safer on mobile. Second, if any single file fails to decode, the run stops and you get an error rather than a partial zip. Remove the problem file and convert again. Duplicate base names are also a trap: if logo.png and logo.gif both become logo.webp, only one of them survives in the archive.

Formats this converter will not read

HEIC from an iPhone, AVIF, SVG, TIFF, RAW files such as CR2 or NEF, and ICO are all refused, because the conversion relies on what the browser itself can decode. ZillaKit has dedicated pages for several of them: HEIC to JPG, AVIF to JPG, SVG to PNG and PNG to ICO. If you need the output at a specific pixel size as well as a specific format, resize first with the image resizer.

Common questions

Does converting keep my EXIF data?

No. Because each image is redrawn on a canvas and encoded fresh, camera model, date, GPS coordinates and orientation tags are all dropped. That is handy for privacy and annoying if you rely on capture dates. To inspect or strip metadata deliberately, use the EXIF viewer and remover.

What happens to an animated GIF?

Only the first frame survives. The animation is not preserved in any output format here, so a converted GIF becomes a still picture.

Why did my whole batch fail instead of just one file?

The conversion loop stops at the first file the browser cannot decode. A corrupt image or an unusual BMP variant will end the run. Take that file out of the list and start the batch again.

Can I change the size at the same time?

No. Output dimensions always match the input exactly. Format and quality are the only things this page changes.

Is WebP safe to use on my website?

Yes for browsers, which have supported it broadly for years. Be more careful when a file is going into someone else's system, such as a government upload form or an older print workflow, where JPEG or PNG remains the safer choice.