Convert JPG to ICO

This is the thing people find out afterwards, so it belongs first. JPG has no alpha channel — the format simply cannot record that a pixel is see-through. Whatever sits behind your logo in the JPG, usually white, is part of the picture, and it comes through into the icon as a solid rectangle.

On a white browser tab that often looks fine. In a dark-themed taskbar, on a coloured toolbar, or next to a bookmark bar in dark mode, it looks like a white box with something in it. If the mark needs to float, the source has to carry transparency: start from a PNG, or go back and ask for the logo as PNG or SVG.

A favicon is drawn at about 16 pixels. A taskbar icon is 32. That is a canvas smaller than the full stop at the end of this sentence, and a photograph carries thousands of times more detail than can survive the journey down to it.

What survives scaling is silhouette and contrast: one bold shape, two or three colours, clear edges. What does not is faces, text, textures, thin lines and anything with a busy background. If you are converting a photograph because it is the only file you have, expect a coloured smudge and consider cropping hard to the single most recognisable element first.

Icons are square and photographs generally are not. The conversion does not crop for you — cropping means deciding what to throw away, and a tool guessing at that gets it wrong on exactly the images where it matters. What it does instead is centre the picture on a square and leave the rest empty, so a 3:2 frame arrives with a band of nothing above and below it and the picture itself drawn two thirds the height of the icon.

So do it first, in any image editor or even a phone gallery. Crop tightly around the subject rather than keeping the whole frame: an icon has no room for context, and a picture that reads well at full size usually needs to be cropped twice as tight to read at all when it is sixteen pixels across.

Nothing an ICO holds is larger than 256 pixels on an edge, so a bigger JPG is scaled down to fit before anything else happens. The sizes written into the file are then taken from that: the default set is 48, 32 and 16, and "All common sizes" adds 64, 128 and 256.

Ask for a size the JPG cannot support and it is enlarged rather than refused, so a 64-pixel picture converted with "256 px only" comes out blurrier rather than better. The default set is safe from that for almost any source, and it covers the two contexts most people are here for — a browser tab and a Windows shortcut. What it is not is a substitute for hand-drawing the small sizes, which is what an application icon in a crowded taskbar really wants; the entries here are your picture reduced, not redrawn.

The picture is decoded from the JPG and stored inside the ICO as PNG data, which is lossless. So the conversion itself does not add compression artefacts on top of the ones the JPG already has.

What it cannot do is remove them. If the source is a heavily compressed JPG pulled off a website, the blocky edges and the haze around dark lines are in the pixels, and scaling to 256 keeps them in proportion. Starting from the highest-quality copy you have is worth more here than any setting.

Put it at the root of the site as favicon.ico. Browsers have requested that exact path for nearly thirty years and still do, whatever your HTML declares, so having it there also stops a steady trickle of 404s in the server log.

If the icon does not change when you reload, that is caching rather than a failed conversion — favicons are cached unusually aggressively. A hard reload, a private window, or appending a query string to the link in your HTML will show you the new one.

ICO is the format Windows uses for executables, folders and shortcuts, and the shell picks whichever entry matches the view it is drawing — so "All common sizes" is the one to choose here, since Explorer draws icons anywhere from 16 pixels in a details list to 256 on a large-tile view. Right-click the shortcut, choose Properties, then Change Icon, and point it at the file.

Keep the ICO somewhere permanent before you do this. Windows stores the path rather than a copy, so an icon set from the Downloads folder disappears the moment the folder is cleared out.

Drop up to 100 JPG files in one go. Each converts separately on your own machine, keeps its filename with the extension swapped, and the batch comes back as a single ZIP — useful when a set of internal tools or shortcuts all need their own icon.

Nothing is uploaded at any point. The conversion runs in the browser tab on your own processor, so there is no queue behind other people and no daily allowance to exhaust.