PNG to BMP

BMP is the simplest image format Windows knows, and that simplicity keeps it alive in game modding, embedded projects, old desktop software, industrial equipment and coding exercises. Converting a PNG to BMP sounds trivial, until transparency gets involved. This converter gives you control over that and writes clean, standard bitmaps.

Two kinds of BMP

The classic 24-bit BMP stores red, green and blue for each pixel and nothing else. Every BMP reader understands it. The 32-bit variant adds a fourth byte for transparency, described in an extended header introduced with Windows 95. Many modern programs read it correctly, but older software, some hardware tools and certain libraries ignore the alpha byte or reject the file.

The default: solid background, maximum compatibility

With “Keep transparency” off, transparent and semi-transparent areas of the PNG are blended onto a background color, white unless you choose another, and a 24-bit BMP is written. Soft edges are blended smoothly instead of being cut. Choose the background to match where the image will appear: black for a dark game menu, a specific gray for a machine interface.

Keeping transparency

Switch it on and the converter writes a 32-bit BMP with explicit color masks, a form that Windows, browsers, GIMP and most engines read with transparency intact. If the PNG turns out to be fully opaque, the converter still writes 24-bit, because an alpha channel full of solid pixels adds size and risk for no benefit.

File sizes

BMP has no compression. Size is simply pixels times bytes per pixel: about 3 bytes for 24-bit and 4 for 32-bit. A 1024 × 1024 texture becomes 3 or 4 MB; a full-HD screenshot about 6 or 8 MB. PNG is usually many times smaller, so expect the converted files to be large. “Limit size” scales big images down by their longest side.

Typical uses

Game modders replacing textures or menu art in older titles, makers loading images onto LCD screens from microcontrollers, technicians feeding logos to label printers or machine controllers, students whose assignment reads BMP files in C or Python, and anyone with a legacy program that has no PNG support.

Checking the bitmap

Windows Photos and Paint display both variants. Paint shows a 32-bit BMP’s transparent areas against white or black depending on the version, which can make it look as if transparency was lost even when it is there. The real test is the program the file is meant for.

Exact sizes for hardware

Displays and printers driven by microcontrollers rarely scale images. If a screen is 240 × 320 pixels, the bitmap should be exactly that size, or the code that draws it may crash or show garbage. Resize the PNG to the precise dimensions with the Image Resizer before converting. Remember that many such displays use 16-bit color internally; their libraries convert from 24-bit BMP when loading.

Batch conversion

Add many PNGs at once, such as a folder of sprites or icons. Each converts on its own; download them individually or all together. Nothing is uploaded, which is useful for unreleased game assets.

Related tools

For photos without transparency, JPG to BMP follows the same steps. To go back to a compact format, BMP to JPG and BMP to WebP shrink bitmaps for sharing.