SquareImage

PNG to ICO Converter

Convert one PNG, JPG or WebP into a real Windows ICO container with the exact layers you need. Crop or pad the source to a square, preserve transparent edges, and download the file without sending the image to a server.

PNG to ICO Converter, at a glance

PNG to ICO Converter on SquareImage.dev packs any PNG, JPEG or WebP image into a binary Windows .ico file containing selectable 16x16, 24x24, 32x32, 48x48, 64x64, 128x128 and 256x256 PNG layers. Full 32-bit RGBA alpha transparency is preserved, and stepped 2x downsampling keeps 16x16 and 32x32 icons sharp. Non-square images can be centred or cropped to 1:1 with optional rounded corners right in the browser with no server upload.

By · Verified

How does a real .ico file differ from a renamed .png?

Renaming a file changes its extension, not its bytes. A real ICO begins with an ICONDIR header, lists each image in a 16-byte directory entry, and stores the PNG payloads at the offsets in that directory. Windows can then choose a layer that matches the requested display size.

Which icon sizes should I include inside a Windows .ico file?

Include 16x16 and 32x32 for compact lists and standard desktop surfaces, 48x48 for larger views, and 256x256 for high-resolution Explorer views. The 24, 64 and 128-pixel options help software that asks for those intermediate sizes.

How do I convert a PNG to ICO without losing transparency?

  1. Choose the PNG. Transparent source pixels remain available to Canvas.
  2. Use transparent padding. This keeps a rectangular logo intact without adding a matte.
  3. Select the layers. Choose every size the target program expects.
  4. Download favicon.ico. Each layer is stored as a full RGBA PNG stream.

Why does stepped downsampling matter for 16x16 icons?

Reducing a 1024-pixel logo directly to 16 pixels asks one resampling pass to discard almost all of the source. Halving it through intermediate canvases gives the smoothing filter smaller decisions and produces steadier edges at the final size. Always check that lettering is still legible at 16x16.

How does PNG to ICO compare with the other tools on SquareImage.dev?

Use the Favicon Generator when a website also needs Apple, Android and manifest files. Use Rounded Corners for a normal transparent PNG or WebP, or Square Crop when the exact 1:1 framing needs manual control before conversion.

Frequently asked questions

Can I convert JPG or WebP to ICO too?

Yes. The browser can decode PNG, JPEG, WebP, GIF and BMP sources. JPEG has no source transparency, while PNG and WebP alpha can remain transparent in every ICO layer.

How many sizes can one ICO contain?

This converter offers seven selectable layers: 16, 24, 32, 48, 64, 128 and 256 pixels square. Select at least one; including several lets each program choose its closest match.

Does the converter preserve transparent pixels?

Yes. Every image is encoded as a 32-bit RGBA PNG payload inside the ICO container, so transparent and semi-transparent edges are preserved.

Why is 256x256 stored differently in an ICO directory?

The ICO width and height fields are one byte each. By specification, a zero value in those fields means 256 pixels, so the 256x256 layer is valid even though the directory byte reads zero.

Is the PNG sent to a conversion server?

No. The browser draws each selected size with Canvas and JavaScript writes the ICO header, directory entries and PNG payloads locally.

Every tool on this site draws your photo onto an HTML canvas and reads the result back out — that is the whole pipeline, which is why nothing is uploaded and why the export size behaves the way it does. The browser's own documentation describes the drawing step:

“drawImage() will always use the source element's intrinsic size in CSS pixels when drawing, cropping, and/or scaling.”
— MDN Web Docs, CanvasRenderingContext2D: drawImage() method

Sources

Links checked 2026-09-03.

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