Why was my BMP rejected?

The tool accepts a file whose reported type is a bitmap or whose name ends in .bmp. Anything else, such as a JPG or PNG, shows the message asking for a BMP image file.

Does it preserve the aspect ratio?

Yes. The picture is scaled to fit inside the square with its proportions intact and centered, and the padding is transparent. Crop the bitmap square first if you want it to fill the icon edge to edge.

Is the download a proper ICO container?

Yes. Browsers cannot export image/x-icon, so the tool writes the ICO structure itself: a six-byte icon directory, one directory entry and a PNG image as the payload, which is valid in the ICO format.

What sizes can I choose?

Multiples of 16 from 16 through 256. Common favicon sizes such as 16, 32, 48, 64, 128 and 256 all fall on the slider steps.

Image manipulation toolsInstantPrivateNo account

BMP to ICO Converter

A dedicated converter that resizes a BMP to a square icon size between 16 and 256 pixels.

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About BMP to ICO

A dedicated converter that resizes a BMP to a square icon size between 16 and 256 pixels. It is intended for older bitmap artwork that you want to use as a favicon or app icon. A bitmap that is not square is fitted inside the square and centered on transparent padding, never stretched.

How to use it

Press Upload, or use the file field, and choose a .bmp file.
Check the Original BMP preview that appears next to the settings.
Move the Icon Size slider, which runs from 16 to 256 in steps of 16 and starts at 32.
Click Convert to ICO and look at the Converted ICO preview.
Choose Download ICO to save the file under the original name with an .ico extension.

Wide bitmap fitted into an icon

Input

A 100×50 BMP with Icon Size set to 32.

Output

A 32×32 icon. Both sides are scaled by 0.32, giving a 32×16 picture centered in the square with 8 transparent pixels above and 8 below. Nothing is distorted, and square sources fill the whole icon.

When to use it

Turning a square legacy bitmap logo into a favicon.
Producing a Windows application icon from an old drawing program export.
Generating several icon sizes of a square graphic by running it through at 16, 32 and 64.

Good to know. The icon holds a single image at the size you chose. If a platform wants several sizes bundled together, run the conversion once per size and combine them in an icon editor.

Questions about BMP to ICO

Why was my BMP rejected?: The tool accepts a file whose reported type is a bitmap or whose name ends in .bmp. Anything else, such as a JPG or PNG, shows the message asking for a BMP image file.
Does it preserve the aspect ratio?: Yes. The picture is scaled to fit inside the square with its proportions intact and centered, and the padding is transparent. Crop the bitmap square first if you want it to fill the icon edge to edge.
Is the download a proper ICO container?: Yes. Browsers cannot export image/x-icon, so the tool writes the ICO structure itself: a six-byte icon directory, one directory entry and a PNG image as the payload, which is valid in the ICO format.
What sizes can I choose?: Multiples of 16 from 16 through 256. Common favicon sizes such as 16, 32, 48, 64, 128 and 256 all fall on the slider steps.

Related tools

Image manipulation toolsInstantPrivateNo account

BMP to ICO Converter

A dedicated converter that resizes a BMP to a square icon size between 16 and 256 pixels.

Back to category

WorkbenchClient-side · Private