Skip to content
keyMotio

Image Converter

Convert images between PNG, JPG, WebP and AVIF, several at once. Set the quality and a maximum width if you want, and you get every file converted with its size before and after, ready to download one by one or all together in a ZIP. It runs entirely in your browser, so a folder of holiday photos never leaves your computer.

Convert to

Around 30% smaller than JPG at the same quality, and it keeps transparency.

Quality85%

85% is where almost nobody sees the difference. Below 60% it starts to show on photographs.

Maximum width

Images wider than this are scaled down, keeping their proportions. Smaller ones are left alone.

How to convert an image

  1. 1

    Add your images

    Drag them onto the box or click to pick several at once. Anything your browser can read works: PNG, JPG, WebP, AVIF, and usually SVG and BMP too.

  2. 2

    Pick the format

    WebP is the sensible default for the web: around 30% smaller than JPG at the same quality, and it keeps transparency. A format your browser cannot write is shown greyed out.

  3. 3

    Adjust quality and size

    The quality slider only appears for formats that have one — PNG does not. You can also cap the width, which is usually what actually makes a photo lighter.

  4. 4

    Download

    Each result shows its old and new size, with a button of its own. With more than one image, a single button packs them all into a ZIP.

What makes it different

  • It does not lie about the format

    Browsers do something nasty here: asked for a format they cannot write, they return a PNG and say nothing. So the format you asked for is checked against what actually came out, and if they differ you are told — instead of downloading a PNG with an .avif name.

  • The formats offered are the ones that really work

    Each one is tested at load time by encoding a one-pixel image and looking at what comes back. There is no API that answers “can you write AVIF”, so trying it is the only reliable way.

  • Whole folders at once

    Drop in fifty photos and get fifty files, each keeping its own name with the extension swapped. Renumbering a batch would destroy the order you had them in.

  • Transparency does not turn black

    JPG has no alpha channel, so a transparent PNG converted to JPG normally comes out with black patches. Here you pick the colour that goes behind, and white is the default.

  • Nothing is uploaded

    Every image is decoded and re-encoded by your own browser. Nothing is sent to a server, so a folder of personal photos stays personal, and there is no queue and no watermark.

Supported formats

In: anything your browser can decode as an image — PNG, JPG, WebP, AVIF and usually SVG and BMP. Out: PNG, JPG, WebP and AVIF, as far as your browser can write them. WebP works everywhere modern; AVIF encoding is available in Chrome and Edge, and the option is disabled where it is not.

Frequently asked questions

Which format should I choose?
WebP for the web: clearly smaller than JPG at the same quality, with transparency, and readable in every current browser. JPG when something old has to open it. PNG when you need it lossless, for screenshots or line art. AVIF when size matters more than compatibility.
Why is AVIF greyed out?
Because your browser cannot write it. Reading and writing are different things: a browser can display AVIF perfectly and have no encoder for it. Chrome and Edge can; Firefox and Safari cannot, at the time of writing.
Does converting lose quality?
Going to PNG does not, it is lossless. JPG, WebP and AVIF do compress with loss, which is why the quality control exists — 85% is where almost nobody sees the difference. And converting a JPG to another lossy format compresses something already compressed, so it is best not to go round in circles.
Why is my converted file bigger?
Usually because you converted a photograph to PNG: PNG is lossless and terrible at photographs. It can also happen going from a heavily compressed JPG to a high WebP quality. The sizes are shown side by side so you can see it instead of guessing.
Is there a limit on how many images?
No fixed count — they are converted one at a time and only the current one is held in memory. Each file can be up to 40 MB.
Are my images uploaded?
No. All the work happens in your browser, and no file is sent anywhere. That is the whole point: converting holiday photos should not mean handing them to a stranger's server.