Output format
Original
Converted
Image converter & compressor
Convert and compress images to PNG, JPEG or WebP, resize by width and compare file sizes, entirely in your browser. Nothing is uploaded; your images never leave your device.
Reading, decoding and re-encoding all run in your browser with the canvas and FileReader APIs. Your images are never uploaded and the tool works offline. Exports are limited to the three formats the HTML canvas can encode (PNG, JPEG, WebP), and animated GIFs are flattened to a single frame.
How the image converter works
Drop an image onto the box above, or click to choose one, and the tool reads it with the FileReader API and paints it onto an HTML canvas. From there it re-encodes the pixels into the format you pick and hands you the result: original and converted sit side by side so you can compare size and dimensions at a glance. Everything happens inside the page: the moment your file is decoded it lives only in your browser's memory, and the converted copy is built with the canvas toBlob method. Pick a format, nudge the quality, optionally cap the width, then download.
PNG, JPEG or WebP: which format should you pick?
PNG is lossless: it keeps every pixel exactly and supports transparency, which makes it perfect for logos, icons, screenshots and any graphic with flat colour and crisp edges, but it is a poor fit for photographs, where it produces huge files. JPEG is the opposite: a lossy format tuned for photos and complex gradients, tiny at sensible quality settings, but with no transparency and visible artefacts when pushed too far. WebP is the modern all-rounder: it does both lossy and lossless, keeps transparency, and is usually 25–35% smaller than the equivalent JPEG or PNG. Every current browser now displays WebP, so it is often the best default for the web.
How the quality slider and resizing shrink a file
Two levers control the final size. The quality slider, shown for JPEG and WebP, sets how aggressively the encoder discards detail: 100% keeps the most information, while lower values trade fine detail for a smaller file. The biggest safe savings usually sit between 70% and 85%. The second lever is dimensions: an image straight off a phone can be 4,000 pixels wide, far more than a website ever shows. Setting a max width, say 1,280 or 1,600, scales it down while keeping the aspect ratio, and because file size grows with the square of the dimensions, halving the width can quarter the bytes. Combine a sensible width with WebP at around 80% and most photos shrink dramatically.
Is anything uploaded? Privacy and limits
Nothing leaves your device. Reading, decoding and encoding all run locally through native browser APIs, so the tool works offline and never touches a server, ideal for private screenshots, ID scans or unreleased artwork. The limits are the browser's own: very large images can be slow to encode, animated GIFs collapse to their first frame because a canvas holds a single still, and re-encoding an already-lossy JPEG loses a little more detail each time, so always keep your original as the master copy.
Frequently asked questions
Does the image converter upload my files anywhere?
No. Your image is read with the browser's FileReader API, decoded onto a canvas and re-encoded entirely on your device. Nothing is ever sent to a server, and the tool keeps working with your connection switched off. That makes it safe for screenshots, scans and photos you would rather not upload.
Which formats can I convert between?
You can drop in almost any image the browser can open (PNG, JPEG, WebP, GIF, BMP or SVG) and export it as PNG, JPEG or WebP. Those three are the formats the HTML canvas can reliably encode. Animated GIFs are flattened to a single frame, since a canvas only ever holds one still image.
How do I compress an image without ruining the quality?
Choose JPEG or WebP, then lower the quality slider gradually while watching the converted preview. Most photos look identical to the eye down to around 75–80% quality while shedding half their size or more. If the picture still looks sharp, keep going; stop as soon as you notice soft edges or blocky patches.
Why is my converted image larger than the original?
Re-encoding never guarantees a smaller file. Saving a detailed photograph as PNG, a lossless format, can easily double its size compared with the original JPEG. For photos pick JPEG or WebP; reserve PNG for graphics, logos and screenshots with flat colour and sharp edges, where it stays both small and crisp.
Does converting to JPEG remove transparency?
Yes. JPEG has no alpha channel, so transparent areas have to be filled when you export to it. If you need to keep transparency, export as PNG or WebP instead. Both preserve the alpha channel. This tool fills transparency with solid white for JPEG, so you never get an unexpected black background.