PNG to ICO Converter

This PNG to ICO converter turns an image into a Windows icon file — most often a favicon.ico for a website — directly in your browser. Pick the sizes you need (16, 24, 32, 48, 64, 128 or 256 px; 16, 32 and 48 are ticked by default) and you get a single .ico file that holds every size, so browsers and Windows can each pick the one that fits.

An .ico file is a small container. It starts with a 6-byte header saying how many images it holds, then one 16-byte directory entry per image giving its width, height, colour depth, byte length and position in the file, then the images themselves. The width and height fields are a single byte each, so a 256 px image is recorded as 0. Originally every image inside was a Windows bitmap; since Windows Vista an entry may instead be a complete PNG file, which is smaller and keeps full 8-bit transparency. This tool stores every size as a 32-bit PNG. Windows Vista and later read that, and we checked that the icons this tool writes decode in Chromium-based and WebKit-based browsers.

One compatibility note, stated honestly: Microsoft's older design guidance (written for Windows 7) suggests PNG-compressing only the 256 px image and keeping bitmaps for the small sizes, for the benefit of pre-Vista software. That matters only for Windows XP-era programs; for a website favicon it does not.

How the sizes are drawn: your browser decodes the image, and for each size draws it onto a transparent square canvas with high-quality smoothing. Every size is drawn from the source image itself, never from the previous, smaller size; for large reductions the browser shrinks in halving steps first, which avoids jagged edges. If the image is not square you choose what happens: "Pad with transparency" fits the whole image and leaves transparent bands, while "Crop the centre" cuts out the middle square. An SVG is first drawn at 512 px so every icon size is sharp. If the source is smaller than the largest size you tick, the tool warns you that the icon is enlarged and will look soft; start from an image of at least 256 × 256 for the best result.

After converting, the page gives you the <link rel="icon"> tag for your HTML with a Copy button. Put favicon.ico at the root of your site; browsers also request /favicon.ico there by default.

Nothing is uploaded. The image is read, drawn and packed into the .ico inside the page; you can confirm in your browser's developer tools (Network tab) that no request carries your file. Small icons simplify detail, so logos with fine text often need a simplified version for 16 px.

1. The file's signature is checked: PNG, JPG, WebP or SVG are accepted, whatever the file is called. 2. The chosen sizes are validated (16, 24, 32, 48, 64, 128, 256), de-duplicated and sorted smallest first. 3. The image is decoded by the browser; an SVG is rendered with its longer side at 512 px. 4. For each size S: pad → scale so the longer side is S and centre it; crop → take the centred square whose side is the shorter side and scale it to S × S. It is drawn with high-quality smoothing onto a transparent S × S canvas and encoded as PNG. 5. The .ico is assembled: ICONDIR (reserved 0, type 1, count), one ICONDIRENTRY per image (width and height bytes, 0 meaning 256; colour count 0; planes 1; 32 bits per pixel; data length; data offset), then the PNG data in the same order. 6. The <link> tag lists the sizes the file actually contains.