🖼 Image to ICO Converter
An Image to ICO Converter is a free online tool that turns PNG and JPG images into ICO icon files for Windows. Upload an image, choose the output sizes, and download a multi-resolution icon with transparency support. The conversion runs in your browser, keeping files private with no signup. Web developers and app makers use it to prepare favicons.
Turn PNG or JPG images into .ico icon files instantly. Multi-size output, transparent background support, and everything runs locally in your browser.
Your image never leaves your device.
What is this tool?
An ICO file is the icon format used by Windows for program shortcuts, folders, and favicons. Unlike a plain PNG, an ICO can bundle several image sizes (16×16, 32×32, 48×48, 64×64, 128×128 and 256×256) inside a single file, so Windows always picks the sharpest version for the current context — a small icon for the taskbar, a large one for desktop shortcuts, and a full-size one for high-DPI displays. This tool converts any PNG or JPG into a standards-compliant multi-size ICO file in a few clicks. The image is drawn onto a canvas at every size you select and packed into the ICO binary format using PNG compression for the 256×256 entry and BMP (DIB) encoding for the smaller sizes, which is exactly how professional icon tools work. Transparent areas in your source PNG are preserved, so icons with rounded corners or cut-out shapes stay crisp. Everything happens in your browser — no upload, no server, no file leaves your device. The resulting .ico file can be used as a Windows application icon, a website favicon, a folder icon, or any other place that expects the ICO format.How it works
The ICO file format is a simple container: a 6-byte header (ICONDIR) is followed by a series of 16-byte directory entries, each pointing to the raw image data for one size. This tool builds that structure programmatically. For every size you select, the source image is drawn onto an off-screen canvas with a transparent background, scaled proportionally and centered. For the 256×256 entry, the canvas is encoded to PNG bytes via the browser’s native encoder. For smaller sizes, the pixel buffer is written as a 32-bit BGRA bitmap (BITMAPINFOHEADER) with the rows stored bottom-up, which is what Windows expects inside an ICO. All entries are then assembled into the final binary and served as a downloadable .ico file. Because the conversion uses the browser’s built-in image and canvas APIs, the result is pixel-accurate and the whole process is fully offline. Source formats supported: PNG (with transparency) and JPG (no alpha channel).How to use
- Click the file picker and choose a PNG or JPG image from your device.
- Tick the icon sizes you want to include — selecting all six (16 to 256 px) gives the most versatile icon.
- Press the Convert button; the ICO file is generated locally in your browser.
- Your download starts automatically with the .ico extension.
- Use the file as a favicon, Windows shortcut icon, or app icon wherever needed.
Frequently Asked Questions
Frequently Asked Questions
What is an ICO file?
ICO is the icon container format used by Windows for shortcuts, folders, executables and applications. It can hold multiple sizes of the same image in one file, so the operating system always renders the most appropriate size for the context. It is also the classic format for website favicons.
Can I keep transparency in my icon?
Yes. If your source is a PNG with transparent areas, those are preserved in the output ICO. The smaller sizes are encoded as 32-bit bitmaps with an alpha channel, and the 256×256 entry is stored as a compressed PNG, which natively supports transparency.
Which sizes should I include?
For maximum compatibility include all six sizes (16, 32, 48, 64, 128 and 256 pixels). Windows uses 16×16 in the taskbar, 32×32 on the desktop, 48×48 in file explorer, and 256×256 for high-DPI displays. If you only need a favicon, 32×32 and 64×64 are usually enough.
Is my image uploaded to any server?
No. The entire conversion runs locally inside your browser using the HTML5 canvas API. Your image is never transmitted, uploaded, or stored anywhere — you can convert sensitive logos or designs with complete privacy.
Tips & Advice
For websites, generate a 32×32 and a 64×64 icon for the favicon, then declare them in your HTML with the shortcut icon link tags for the best cross-browser results. For Windows applications, a multi-size icon with 256×256 included gives you crisp icons on Retina and high-DPI screens. If your source image is not square, the tool scales it proportionally and centers it on a transparent background, so nothing is cropped or stretched. Prefer a PNG source whenever possible: PNG keeps the alpha channel, while JPG has no transparency. After converting, you can verify the icon by opening it in any image viewer — most modern viewers display all embedded sizes. Keep the original PNG as a master copy; regenerating the ICO later is always one click away.
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