JPG to BMP: Creating Uncompressed Windows Bitmap Files
When BMP Format Is Needed
BMP (Bitmap Image File) is the native raster image format of Microsoft Windows. While mostly superseded by PNG and JPEG for modern use, BMP remains required by certain legacy Windows applications, industrial control systems, specialized hardware interfaces, some CAD applications, and older embedded systems. If your software specifically requires BMP format and will not accept JPEG or PNG, this converter will create a proper Windows BMP file.
What Is BMP?
BMP stores image data as a grid of pixels with each pixel storing its full color value in 24 or 32 bits. There is no compression applied to the pixel data, making BMP files very large but also very simple to read. Every Windows program, going back to Windows 3.1, can open BMP files. This universal Windows compatibility is the main reason BMP still exists in specialized contexts.
BMP vs JPG
JPEG uses lossy compression to store photographic images efficiently. A 200 KB JPEG might expand to a 6 MB BMP because BMP stores every pixel without compression. The BMP will be larger but is required when the receiving application needs uncompressed pixel data. The visual appearance will be essentially the same as the JPEG source since BMP simply stores the pixel values from the JPEG without further modification.
Historical Uses of BMP
In the early Windows era, BMP was the standard format for desktop wallpapers. Windows 3.x, 95, 98, and XP all used BMP format for wallpaper images. Applications like MS Paint defaulted to saving in BMP format. Many Windows API functions dealing with icons, cursors, and device-independent bitmaps use BMP internally. Industrial software developed for Windows in the 1990s and 2000s often saved and loaded images in BMP format.
This Tool Uses a Custom BMP Encoder
Standard web browsers cannot natively export images in BMP format through the Canvas API. This tool uses a custom JavaScript BMP encoder (encoder-bmp.js) to construct proper Windows BMP files from scratch. The encoder creates a standard Windows DIB (Device-Independent Bitmap) with a BITMAPFILEHEADER and BITMAPINFOHEADER, ensuring compatibility with all Windows applications that expect BMP format.
How to Convert JPG to BMP
- Select your JPEG file — click the upload area or drag and drop your JPG or JPEG file.
- Preview — your image is displayed for confirmation.
- Click Convert to BMP — the custom BMP encoder creates a proper Windows BMP file in your browser.
- Download — save the BMP file for use in your Windows application.
About This Tool
This JPG to BMP converter uses a custom JavaScript BMP encoder that runs entirely in your browser. No file is uploaded to any server. Your images remain private on your device. Free to use with no registration and no watermarks.