Boneyard Tools

ICO and CUR Icon Inspector

Drop in a Windows ICO or CUR file to see what is packed inside it. The inspector reads the icon directory and lists every contained image: its pixel size, bit depth, palette color count, byte size, and whether that frame is stored as a PNG or a classic BMP. The file is read entirely in your browser and never uploaded.

How to inspect an ICO or CUR file

  1. Drag an .ico or .cur file onto the box, or click browse to pick one.
  2. Read the directory summary: type, image count, and the per-frame table.
  3. Check the size and PNG or BMP column to confirm the resolutions you need.

Examples

A multi-resolution favicon

favicon.ico (a multi-size icon)
Icon, 3 images: 16x16, 32x32, 48x48, all 32-bit BMP

Frequently asked questions

Is my ICO file uploaded anywhere?

No. The file is read and parsed entirely in your browser using JavaScript. Nothing is sent to a server, so your icons and cursors never leave your device.

What does this tool show me?

It reads the icon directory and lists every image inside the file: its width and height, bit depth, palette color count, byte size, the offset of its data, and whether the frame is stored as a PNG or a BMP.

Why does my 256x256 frame show as a PNG?

Since Windows Vista, large icon frames are usually stored as compressed PNG data inside the ICO instead of an uncompressed BMP. The inspector detects the PNG signature and labels those frames so you can tell them apart.

What is the difference between an ICO and a CUR file?

They share the same directory format. ICO files are icons (resource type 1) and CUR files are cursors (resource type 2). This tool reads both and tells you which one you opened.

Why does a size show as 256 when the file says 0?

Each directory entry stores width and height in a single byte, so the largest value it can hold is 255. A stored byte of 0 is the agreed convention for a 256 pixel dimension, which the inspector decodes for you.

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