How to Save an Image as an ICO File

To save an image as an ICO file, export or convert the image data to the .ico format; changing the filename extension alone does not convert it. For a graphical workflow, use GIMP’s File → Export As and choose Microsoft Windows Icon. For a repeatable command-line workflow, ImageMagick can make one ICO containing several standard icon sizes.

What an ICO file contains—and why the details matter

An ICO file can contain multiple icon images at different sizes, rather than just one bitmap. This lets Windows or another supporting application select an image suited to the size at which the icon is being displayed. Microsoft identifies 16, 32, 48 and 256 pixels as common icon resource sizes; including a size family can avoid relying on a single image being scaled up or down. Microsoft’s icon overview was updated on September 21, 2026.

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ICO is a file format, not a special kind of filename. Renaming picture.png to picture.ico leaves the image data unchanged. Use an export or conversion tool that actually writes ICO data, then check that the resulting file works in the program or system where you intend to use it.

Choose a conversion method

Neither method is universally best. Use GIMP if you prefer to inspect and choose export settings in a graphical interface. Use ImageMagick if you want a command you can reuse or automate.

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Export an image to ICO in GIMP

1. Open the source image. Start GIMP and open the image you want to use. If the design has fine details, inspect how it reads at the small size where the icon will appear; an image that looks clear when enlarged may become indistinct at icon scale.
2. Open the export dialog. Select File → Export As. Enter a destination filename ending in .ico, such as app-icon.ico, and continue to the export options. GIMP’s version 3.2 documentation describes exporting through this dialog as a Microsoft Windows Icon.
3. Choose the Microsoft Windows Icon format. If GIMP does not select the format based on the filename, choose the ICO export type in the dialog. A filename ending in .ico is not enough by itself; the export needs to use the ICO format.
4. Select sizes and encoding options. GIMP’s ICO options let you choose image sizes and color depths. The documented choices include 1, 4 and 8 bits per pixel, 24 bpp with 1-bit alpha, and 32 bpp with 8-bit alpha. The GIMP guide describes 32 bpp with alpha as the most common format. The right selection depends on the target software and the appearance you need.
5. Export and inspect the result. Confirm the settings and save the file. Check that it opens and that transparency, visible detail and included sizes behave as expected in the intended application. If a program rejects the file, try an encoding it supports rather than assuming every ICO variant is accepted.

Transparency and color depth

Transparency is part of the image data and export settings; it does not appear simply because a filename ends in .ico. GIMP offers 32 bpp with an 8-bit alpha channel. If the icon needs smooth transparent edges, select an alpha-capable option and inspect the exported image against both light and dark backgrounds.

Older Windows or Visual Studio design guidance may describe requirements for a particular platform era or asset workflow. Do not treat those recommendations as universal requirements for every modern ICO use. Follow the consuming application’s own specifications where they are available.

PNG-compressed image data inside ICO

GIMP’s documentation notes that an ICO can use PNG-compressed image data to reduce stored image data, but warns that not all programs support that icon type. Choose PNG compression when the software that will consume the icon supports it. If compatibility is uncertain, use an alternative supported encoding or test the exported file directly in that software.

Convert PNG to ICO with ImageMagick

ImageMagick documents this command to create an ICO from a PNG with several common sizes:

magick input.png -define icon:auto-resize="256,128,96,64,48,32,16" output.ico

Replace input.png with the path to your source image and output.ico with the destination path. For example, if the source is in the current directory and is named logo.png, the command is:

magick logo.png -define icon:auto-resize="256,128,96,64,48,32,16" logo.ico

The resize definition requests 256, 128, 96, 64, 48, 32 and 16 pixel icon sizes. The ImageMagick example documents this multi-size ICO approach; the exact behavior can depend on the installed ImageMagick build and its supported input decoders. ImageMagick describes magick as a format-conversion and image-resizing command-line tool.

When the command fails

• Check that magick is available as a command in your terminal. If the command is not found, the shell cannot locate an ImageMagick installation.
• Check the input path and filename, including the extension and capitalization where your filesystem distinguishes it.
• If ImageMagick reports that it cannot read the source, the installed build may not support that input format, or the file may not be readable as an image. Try a supported source format such as PNG.
• If the command completes but the icon does not work in the destination application, verify the ICO output and try another encoding or tool. A valid conversion does not guarantee that every consuming program supports every ICO encoding.

Pick the right sizes and check the icon at actual scale

For a Windows icon, Microsoft’s overview lists 16, 32, 48 and 256 pixels as common resource sizes. The ImageMagick example includes those and additional sizes: 64, 96 and 128 pixels. Which sizes matter depends on the target context; neither list is a guarantee that every application requires every size.

Look at the icon at its intended display size before relying on it. Remove or simplify details that disappear when reduced, and check that the silhouette and important elements remain recognizable. A multi-size ICO gives the consuming software more than one image to choose from, but it cannot make a design legible if its key details are too fine.

Use ICO for a website favicon only when it fits the site

An ICO can be useful for a website favicon, but it is not the only image format browsers may accept. ImageMagick’s format documentation notes broadly that many browsers accept other image formats too; that statement is not a current compatibility matrix for every browser and platform. Check the requirements of the site’s target browsers and the way the favicon is declared before deciding which files to publish.

For a favicon, verify the finished file in the actual browser and site setup. Do not assume that a Windows icon’s size family, transparency or encoding choice automatically matches every web deployment’s needs.

Common problems and fixes

The file has an ICO extension but will not open

The image may have been renamed rather than exported. Reopen the source in GIMP, use File → Export As, and select Microsoft Windows Icon, or use a conversion command that writes ICO data.

The icon appears with a solid background

Check that the source has transparency and that you selected an export option with an alpha channel, such as GIMP’s documented 32 bpp with 8-bit alpha option. Then inspect the exported result; the extension alone does not preserve or create transparency.

A program rejects the ICO even though it was exported

Some programs do not support PNG-compressed image data inside ICO. If the export used PNG compression, try an encoding supported by the target application. Verify against that application’s requirements when possible.

The icon looks blurry or loses detail

Inspect it at the size where it will actually appear. A single image scaled to a different size can lose quality; an ICO can contain multiple image sizes. Consider supplying the sizes appropriate to the target context and simplifying details that vanish at small scale.

The ImageMagick output differs from expectations

The documented command depends on the installed ImageMagick build and its input decoder support. Confirm that the source opens correctly, that the command points to the intended file, and that the generated ICO contains usable images for the target program. If the destination program rejects an encoding, test another supported export route.

Or skip the browser setup

ScreenshotNeo is a website screenshot API and MCP server, not an ICO converter. If what you need is a clean screenshot of a web page rather than conversion of an existing image, one GET request can return a PNG, JPEG, WebP or PDF. Its clean-shot steps can accept cookie or consent banners and remove known consent platforms, newsletter popups and chat widgets before capture; each step can be turned off. Bot checks, blank pages, timeouts, failed loads and cache hits are not billed, and response headers identify the page verdict and billing status. AI agents can use its MCP server tools, including take_screenshot, get_page_info and capture_pdf.

Example cURL request for a web screenshot (the returned file is not an ICO):

curl -G "https://api.screenshotneo.com/v1/shot" -d access_key=YOUR_API_KEY --data-urlencode url=https://stripe.com -o shot.webp

See the ScreenshotNeo API documentation for request options. The free plan includes 1,000 screenshots per month with no card; paid plans start at $5 for 3,000. Sign up for ScreenshotNeo to try the free monthly allowance. More about ScreenshotNeo.

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