Little Toolkit

Multi-size ICO generator

Choose icon sizes and a filename, then download a multi-size ICO locally.

Enable JavaScript for interactive processing. You can read the instructions, limits, and FAQs below without it. Files are processed only in your browser.

Multi-size ICO generator User Guide

Import one square PNG or JPG and create a single multi-size ICO in your browser, preserving PNG transparency with a custom download filename.

How to use

  1. Import a square PNG or JPG with sides of at least 256 px.
  2. Select at least one size to include and set the filename.
  3. Click Generate ICO, check the result, then download the ICO file.

Formats and limits

  • Up to 20 MiB per file, 256–4,096 px per side and 16,777,216 pixels. Non-square and animated images are rejected.
  • Choose 16, 24, 32, 48, 64, 128 or 256 px; all are selected by default. JPG backgrounds are not removed.
  • Requires Worker, OffscreenCanvas and createImageBitmap. The limits do not guarantee success on every device; use a smaller image if memory is limited.

Output

One ICO containing every selected size, named favicon.ico by default. The original image is unchanged.

Frequently asked questions

Does this only change the image extension to ICO?

No. The output combines an ICO header, size directory and PNG image data for each size in one ICO file.

How are transparent backgrounds and JPG images handled?

PNG transparency and partial transparency are preserved while resizing. JPG stays opaque; its background is not removed.

The file name and content are only processed in your browser and are not transmitted to the server. The original file will not be overwritten. Please export the required results before leaving the tool.