PNG to ICO Converter

A PNG to ICO converter packs square copies of a PNG image, one per size you ask for, into a single .ico file. That is the part most people get wrong on the first try: an .ico is not one image with an unusual extension, it is a small container with a directory at the front listing every image inside it and where each one starts. Whatever reads the file - a browser drawing a tab, a desktop drawing a shortcut - looks at that directory and takes the entry closest to the size it needs.

This page writes four sizes and they are all ticked when you arrive: 16, 32, 48 and 256 pixels. Each ticked box becomes one square image inside the .ico, stored PNG-compressed with its alpha channel intact, and the sizes are written smallest first. Untick the ones you do not want and the file gets smaller. Untick all four and the converter falls back to writing all four, because an icon with nothing in it is not a useful file. The 256 ceiling is the format talking rather than the tool: an ICO directory entry records its width in a single byte, which is why 256 is the largest image an .ico can carry and why it is stored as the special value zero.

Start from a square PNG that is at least as large as the biggest size you tick. The converter scales your image down to each square, and scaling down is the direction that looks good. Feed it a 64 px source with 256 ticked and the 256 entry is a 64 px image stretched up four times, which is soft and blotchy at exactly the size a high-DPI screen shows off. A 512x512 export from your design tool covers every case with room to spare.

A non-square logo is the other common problem. The converter stretches the image to fill each square rather than letting it overflow or guessing at a crop, and it tells you it did: drop a 1024x256 wordmark and the row reads "The image was 1024x256, so it was stretched to squares of 16, 32, 48, 256 px." A stretched wordmark is unreadable at 16 px anyway. The fix is to decide what the small sizes should show before converting, not after. Usually that means cropping to the symbol on its own, or padding the wordmark onto a square canvas with transparent margins so it keeps its proportions and simply sits smaller inside the icon.

Here is a full run. Take a 512x512 file called logo.png, leave all four boxes ticked and drop it in. It converts straight away: the row shows the input size, an arrow, the output size and the size change, with the note "Contains 16, 32, 48, 256 px icons." under it, and the download icon on the row saves logo.ico. Untick 256 and the file converts again on its own: the same source now produces a much lighter file carrying three images, since the 256 px entry was most of the weight. Drop eight brand PNGs together and Download All (8 images) writes converted-ico.zip with every .ico inside, numbering duplicate names rather than overwriting them.

Everything runs client-side. Your browser decodes the PNG, draws it at each requested size on a canvas, encodes each square as PNG and assembles the .ico in memory, so the artwork never leaves the device and the page keeps working with the network disconnected once it has loaded. Transparency is preserved at every size, and nothing is filled in behind it. Metadata and colour profiles attached to the source are dropped by the canvas step. Images above 100 megapixels are refused with a message, empty files are refused, there is no cap on file size in bytes, and the tool is free, no signup, with a daily limit on conversions.

• Resizing and packing happen client-side with the browser's Canvas API. The PNG and the finished .ico never leave this tab.
• An unreleased logo or brand mark can be converted without handing it to a third-party service.
• The daily usage check sends a file count, the combined size in bytes and the target format. File names and image pixels are not included.
• Metadata and colour profiles in the PNG are not copied into the icon entries.
• Finished icons are held in memory until you remove them, press Clear All or close the tab, and no copy is stored on a server.