JPG to BMP

BMP is one of the oldest image formats on Windows, and it refuses to disappear. Industrial machines, older Windows programs, firmware tools for small LCD and e-paper displays, embroidery and engraving software, some game modding tools and many programming exercises all expect plain bitmaps. This converter turns JPG photos into standard BMP files that such software reads without complaint.

What a BMP file contains

A BMP is close to a raw dump of pixels: a short header with width, height and color depth, followed by the colors of every pixel, row by row. There is no compression, so any program can read it with very little code. That simplicity is exactly why embedded devices and old software rely on it.

Why 24-bit is the safe choice

The converter writes 24-bit color: one byte each for red, green and blue per pixel, with the classic header that every BMP reader since Windows 3 understands. JPG photos have no transparency, so a 32-bit file with an alpha channel would only add size and risk incompatibility. A “Keep transparency” switch is available for sources that really are transparent, but it stays off for normal JPGs.

File size grows a lot

Because BMP does not compress, size depends only on pixel count. Expect roughly 3 bytes per pixel: about 900 KB for 640 × 480, 6 MB for full HD and well over 30 MB for a modern phone photo. If the device or program only needs a small image, switch on “Limit size” and set the longest side, or resize exactly with the Image Resizer first.

Preparing images for small displays

Microcontroller projects with TFT or OLED screens usually want an exact resolution, such as 320 × 240 or 128 × 64. Resize or crop to that size first, then convert. Many display libraries read 24-bit BMP directly from an SD card; others need conversion to their own format, for which a BMP is the usual input. Monochrome e-paper panels may additionally need a dithered black-and-white image, which the Image Dithering Tool can produce.

Quality: nothing lost, nothing gained

The JPG is decoded once and stored as-is. Any blockiness or noise that the JPG compression introduced remains visible in the BMP. What you gain is that further edits and saves of the BMP do not add new compression damage, which can matter for repeated processing steps.

Batch conversion

Drop many JPGs at once, for example a set of frames for a display animation. Each one converts separately and can be downloaded individually or all together. The work happens in your browser, so even large photos are not uploaded anywhere.

Opening the result

Windows Photos, Paint, macOS Preview, GIMP and practically every image viewer open these files. If a specialist program still rejects the BMP, check its documentation for required dimensions or a fixed color depth such as 8-bit, which some very old tools insist on.

When not to use BMP

For websites, email or storage, BMP is wasteful: JPG, PNG or WebP are many times smaller. Use BMP only when the receiving software requires it.

Related tools

For a lossless format that is also compact, JPG to PNG is the better everyday choice. For transparent sources, PNG to BMP can keep the alpha channel. To go back, BMP to JPG shrinks bitmaps for sharing.