What Is a .ico File? .ico Format, MIME & How to Open

Quick facts

Extension.ico

File typeIcon File

MIME typeimage/vnd.microsoft.icon

CategoryImage

Charset—

CompressibleYes

Format familyicon

What is .ico

What is a .ico file?

A .ico file is a Icon File — Windows icon format storing multiple sizes and color depths.

In the mime-db registry it maps to image/vnd.microsoft.icon, and it is marked as compressible. When serving .ico over HTTP, set the Content-Type header as shown in Developer info below.

Related entities: it maps to image/vnd.microsoft.icon — and is delivered over HTTP via the Content-Type header.

How to open .ico files

Use IcoFX or GIMP to open and edit .ico files.
Any text editor (Notepad, VS Code) can inspect the raw content as text.

Developer info

When served over HTTP, responses should set the following header:

Content-Type: image/vnd.microsoft.icon

Common software that reads/writes .ico:

IcoFXGIMPWindows

Relation chain

.icoextension of

format

iconserved as

mime type

image/vnd.microsoft.iconsent via header

http header

Related extensions

Related MIME types

image/vnd.microsoft.icon

.ico

image/x-icon

.ico

Common uses

Web graphics and photos
Design assets and icons
Print and photography

How to edit .ico files

Open the file with IcoFX, make your changes and save.
Most editors preserve the original formatting and encoding — avoid changing the charset.

How to create .ico files

Create a new file and save it with the .ico extension, or export this format from IcoFX.

Frequently asked questions

What programs can open .ico files?

Common options include IcoFX, GIMP, Windows. You can also open many of these files with built-in viewers or a browser.

How do I create a .ico file?

Create a new file in any text editor or the app that owns the format and save it with the .ico extension.

What is the relationship between .ico and the image/vnd.microsoft.icon MIME type?

image/vnd.microsoft.icon is the media type identifier used for .ico files during network transfer (for example in the HTTP Content-Type header).

Sources & standards

Updated 2026-09-13

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