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BMP to JPG Converter
Our free BMP to JPG converter turns a bulky bitmap picture into a much smaller JPG right in your browser. Upload a .bmp file, pick a quality and a background colour, and download a real .jpg file — no upload to any server, no sign-up, and no watermark. A BMP stores every pixel in full with no compression, so it is often ten or twenty times larger than the same picture as a JPG.
Your file stays on your device. It is converted in your browser and never uploaded anywhere.
0.5 is the smallest file, 1.0 is the best quality. 0.85 suits most pictures.
Resizing keeps the picture's proportions — only the width changes.
Any see-through areas in a 32-bit BMP are filled with this colour, because JPG cannot store transparency.
Leave blank to keep the original name with a .jpg ending.
How it works
BMP is one of the oldest picture formats still in use. It was designed for Windows, and it stores a picture in the simplest way possible: a short header, then the colour of every pixel, one after another, with no compression at all. That simplicity has a price. A 24-bit BMP uses three bytes per pixel — one each for blue, green, and red — so a 1920 by 1080 screenshot is 1,920 times 1,080 times 3, which is 6,220,800 bytes of pixel data plus a 54-byte header: about 6.2 MB for a single screen picture. A photo saved as a BMP can easily pass 20 MB, which is why BMP files are awkward to email, slow to load on a web page, and refused by many upload forms.
JPG works the opposite way. It is built for photographs, and it compresses by grouping each picture into small blocks and keeping the parts of each block the eye notices most, while rounding away fine detail that barely registers. How much it rounds away is set by the quality number, from 0 to 1. At quality 1.0 almost nothing is thrown away and the file stays large; at 0.5 a lot is thrown away and the file shrinks sharply, with softer edges and faint block marks in smooth areas. Quality 0.85 sits in the middle: the picture still looks clean at normal viewing size, and the file is usually a tenth to a twentieth of the BMP it came from.
When you pick a file, the tool first checks that it really is a BMP. It looks at the first two bytes, which must be the letters B and M, and reads the header to find the width, the height, the colour depth, and whether the picture is compressed. It accepts uncompressed 24-bit and 32-bit BMP files, which cover the pictures Windows Paint and most screenshot tools produce, and it refuses compressed or damaged files with a plain message instead of a broken download. Then it reads the picture into your browser and draws it onto a canvas, and shows the picture's dimensions and file size so you can see what you are starting with.
Before the JPG is made, the canvas is filled with your background colour. That step matters because JPG has no transparency: a 32-bit BMP can hold see-through pixels, but a JPG cannot, so those pixels have to become some solid colour — white by default, or black, or a colour you pick with the colour picker. The picture is then drawn over that background at the size you chose: original size, 75 percent, half, quarter, or a custom width in pixels, with the height worked out automatically so the picture never stretches. Finally the canvas exports the picture as a JPG at the quality on your slider, from 0.5 to 1.0.
The result is offered as a download named after your original file with the ending changed to .jpg, or the name you typed in the output box. The page shows the original size next to the new size, the saving in kilobytes, and the saving as a percentage, with a side-by-side preview so you can check the picture still looks right before you use it. Because every step happens on your computer, there is no waiting for an upload and no copy of your picture sitting on someone else's server.
Worked example
Suppose you took a screenshot of a full desktop and saved it as screen.bmp. The picture is 1920 by 1080 pixels, 24-bit, and the file is 6,220,854 bytes — 6,220,800 bytes of pixel data plus the 54-byte header — which is about 6.2 MB. The form you need to upload it to only accepts files under 1 MB.
Step 1: you click "Choose a BMP file" and pick screen.bmp. The tool checks the BM header and shows "screen.bmp — 1920 × 1080 px, 24-bit, 6.2 MB" under the file picker.
Step 2: you leave the quality at 0.85, the size on Original, and the background on White, then click "Convert to JPG". The tool draws the picture onto a canvas and exports it as a JPG.
Step 3: the result appears with a side-by-side preview and a download button. The new file is called screen.jpg and is about 350 KB — roughly a seventeenth of the original size. The saving is about 5.9 MB, or about 94 percent, and the screenshot still reads clearly at full screen. You click "Download .jpg" and the file lands in your Downloads folder, well under the form's 1 MB limit.
If the form had needed an even smaller file, you could run the same BMP through again at quality 0.6 and 50 percent size. The file would drop to around 80 KB at 960 by 540 pixels — fine for a web page, but the small text in the screenshot would start to look soft, so 0.85 at full size is the better choice when the text has to stay readable.
FAQ
Is my BMP file uploaded to a server?
No. Your picture is read and converted in your own browser. The file never leaves your device, so private screenshots and scans stay private.
How much smaller will the JPG be than the BMP?
Usually a lot smaller. An uncompressed BMP stores every pixel in full, so a 1920 by 1080 picture is over 6 MB, while the same picture as a JPG at quality 0.85 is often 300 to 500 KB — roughly 15 times smaller. The exact saving depends on how detailed the picture is.
What quality should I choose?
Use the quality slider from 0.5 to 1.0. Quality 0.85 is the sweet spot for most pictures, 0.95 to 1.0 keeps the most detail for images you plan to edit again, and 0.5 to 0.7 makes the smallest file for web pages and messages, with slightly softer edges.
What happens to transparency in my BMP?
JPG has no transparency, so see-through areas cannot stay see-through. The converter fills them with the background colour you pick — white by default, or black or a colour of your choice — before saving the JPG.
Why does the converter reject my file?
The file must be a real BMP: it has to start with the letters BM and hold an uncompressed 24-bit or 32-bit picture. A renamed JPG, a compressed BMP, or a damaged file shows a friendly error instead of a broken download.