JPG to BMP converter.

To convert JPG to BMP, drop your .jpg or .jpeg pictures here and download them as .bmp files. A BMP stores every pixel as it is, with no compression, so the file is many times bigger than the JPG. People still ask for it because some older programs, devices and embedded tools only read BMP. This page converts one picture or a whole batch and shows the size before and after, so the jump is no surprise.

How to convert JPG to BMP

1. Drop your JPG files on the box that says Drop JPG pictures here, or click it to choose them. A folder works too. PNG, WebP, GIF and HEIC pictures are accepted by the same box.
2. Look at the large preview and the list. Each picture shows its old size, its new size and its bit depth.
3. Open Colours if you want something other than the default. Open Size to make big photos smaller before they are written, which cuts the BMP size a lot.
4. Click Download BMP for one picture, or Download all as ZIP for many. In Chrome and Edge, Save all to a folder writes them straight into a folder you pick.

The three colour choices

The first option, 24-bit colour (32-bit if see-through), picks for you: a picture with transparent areas is written as 32-bit, and every other picture as 24-bit. A JPG has no see-through parts, so a JPG always comes out as 24-bit there. If you pick plain 24-bit or 8-bit for a picture that is see-through, the empty areas are filled with the background colour you choose, white by default.

Why a BMP is so big, with numbers

A BMP holds one value per colour channel per pixel and nothing else. Take a photo of 4,000 by 3,000 pixels, which is 12,000,000 pixels.

• 24-bit: 12,000,000 x 3 bytes = 36,000,000 bytes, plus a 54 byte header. About 36 MB.
• 32-bit: 12,000,000 x 4 bytes = 48,000,000 bytes, plus a 122 byte header. About 48 MB.
• 8-bit grey: 12,000,000 x 1 byte = 12,000,000 bytes, plus 1,078 bytes of header and grey palette. About 12 MB.

The same photo as a JPG is often a few megabytes, because JPG throws away detail you are unlikely to see. A BMP cannot, so its size depends only on the width, height and bit depth, never on what is in the picture. A plain white photo and a busy street photo give BMP files of the same size. Setting Size to 1920 px on the longest side turns that photo into 1920 x 1280, which is 2,457,600 pixels, or about 7.4 MB as a 24-bit BMP.

When you download many BMP files, the ZIP is compressed, and BMP data shrinks inside it because pixels repeat. How much depends on the pictures. The summary tells you the real numbers for your files.

What the BMP file contains

Rows are stored from the bottom of the picture to the top, and each row is padded with zero bytes so its length is a multiple of 4. A picture 5 pixels wide has 15 bytes of colour per row at 24-bit, so one zero byte is added to make 16. This page writes that padding for you. Programs that read BMP expect it.

A BMP has no place for the date taken, the camera or the location, so those are not carried over. That also means a BMP cannot leak where a photo was taken.

Good to know

• The width and height in pixels stay the same unless you choose a Size.
• Converting does not add detail. Any blocky patches from the JPG's compression are now fixed in the pixels.
• The name stays with a new ending: cover.jpg becomes cover.bmp.
• A BMP cannot be compressed on its own. If size matters and the program reads other formats, use JPG to PNG, which keeps every pixel in a smaller file.
• Going the other way? The image converter opens BMP files and saves them as JPG, PNG or WebP.