BMP is the plain, uncompressed Windows bitmap. It is rarely the right choice for sharing — the files are huge — but some legacy applications, embedded displays, and image-processing pipelines insist on it because it is dead simple to read pixel by pixel. This tool converts your JPG into a standard BMP whenever a tool or device demands that format.
Inside the BMP format: a header and raw pixels
The Windows bitmap (BMP, also called DIB) is about as simple as a raster file gets. It begins with a small file header and an info header describing width, height, and bit depth, followed by the pixel array stored bottom-up, row by row. Most JPG conversions produce a 24-bit BMP — eight bits each for blue, green, and red, in that BGR order. Two quirks matter when reading the data directly: each pixel row is padded to a multiple of four bytes, and the rows are usually stored from the bottom of the image upward. Because there is no compression and almost no structure to decode, a BMP is trivial for low-level code to parse pixel by pixel, which is precisely why some embedded and legacy systems still ask for it. When you need a more capable lossless container for editing or print, our JPG to TIFF tool is the better choice.
Lossless container, but the JPG quality is already fixed
BMP is technically lossless: once your JPG is decoded to pixels, writing them into a bitmap adds no further compression and no new artefacts. But it is important not to mistake that for a quality gain. The original lossy JPG compression already discarded high-frequency detail and may have introduced blocking, and a BMP faithfully preserves those exact pixels — flaws included. So a JPG-to-BMP conversion is a format change, not a restoration. The cost is size: an uncompressed 24-bit BMP needs roughly three bytes per pixel with no savings at all, so a 12-megapixel photo lands around 36 MB. That is why BMP is impractical for sharing and reserved for pipelines that specifically require an uncompressed bitmap. To learn how these formats fit together, see jpeg2raw.
When BMP is the right call — and when it is not
BMP earns its place in narrow situations rather than everyday use. Reach for it when a tool or device leaves you no choice:
- Legacy Windows software that predates broad PNG or TIFF support.
- Embedded displays and microcontrollers whose firmware reads only raw bitmaps.
- Image-processing scripts that want guaranteed uncompressed input with no decoder dependency.
For almost everything else — websites, email, storage — a compressed format wins decisively on size with no visible penalty. If your real goal is a high-quality master developed from a camera RAW file, that is a different starting point entirely; see our RAW to JPG tool for developing sensor data into shareable photos.