About BMP to PDF
BMP, the Windows bitmap, goes back to the earliest versions of Windows. It stores pixels with little or no compression, which made it easy for software to write and explains why it still turns up: drawings saved from Paint, captures from older programs, exports from medical, industrial and laboratory equipment, and folders of images from decades-old archives. That simplicity is also its weakness. BMP files are large, and many upload forms only accept PDF, JPG or PNG.
This converter reads each bitmap with your browser’s built-in decoder, places it on a white page and stores it as a JPEG inside the PDF. Since bitmap data is typically uncompressed, the PDF usually comes out at a small fraction of the original size even at high quality. You can bundle all the bitmaps into one PDF or create a separate PDF for each file.
Bitmaps whose long side exceeds 2,560 pixels are scaled down to it unless you select another size from the menu, and anything smaller is left at its native dimensions. The 4096, 1920 and 1280 px settings are there when you need more detail or a lighter file.
How to use BMP to PDF
- Choose your BMP filesDrag bitmaps onto the page or open them with the file picker. Up to 500 files can be converted in one go.
- Set up the pagesSelect Letter, A4 or Fit to photo, then decide whether pages follow the date, the file names, or the sequence in which you added the files.
- Convert to PDFChoose a combined document or one PDF per image; conversion starts as soon as the files are added, and Apply new settings redoes it if you change the choice afterwards. A combined file is named after its first and last bitmap; when there are several PDFs, Download all saves them in a ZIP.
When people use it
A drawing made in Paint
Your child drew a birthday card in Paint and saved it as a .bmp. A Letter or A4 PDF of it is easy to email to grandparents and prints at full page size on any printer.
Captures from lab or test equipment
Some microscopes, oscilloscopes and other instruments export their captures as BMP. Collect the images from one session into a single PDF, sorted by file name or date, for a report or a lab notebook.
Clearing out an old backup drive
A drive from the early 2000s is full of scanned letters and photos saved as BMP. Grouping them into PDFs by topic takes far less space and makes them easy to open on any current phone or computer.
Why the PDF ends up so much smaller
A typical BMP stores every pixel as raw color values, so a 1920 by 1080 capture weighs around 6 MB no matter what it shows. JPEG compression inside the PDF usually cuts that to a fraction at the default quality of 92. The cost is a small, normally invisible loss of detail. If a bitmap contains fine text, thin lines or pixel art, set quality to 100: the edges stay clean and the file is still far smaller than the BMP.
Bitmap quirks worth knowing
- Transparency. Most bitmaps have none, but 32-bit BMPs can carry an alpha channel; any transparent pixels become white.
- Tiny images. A small bitmap is stretched to fill the page on Letter and A4, and Fit to photo pages are 11 inches on the long side, so a 32-pixel icon shows up as large blocks or a soft blur depending on the PDF viewer.
- Unusual variants. BMP has several internal versions. The browser handles the common ones; if a file from very old software shows an error, opening it in Paint and saving it again usually fixes it.
- Dates. The BMP format has no field for a capture date, so sorting by date uses each file’s last-modified time.
Limits and privacy
- Writing inside the images isn’t turned into searchable text, because this converter doesn’t run OCR. OCR PDF can add a searchable text layer to the finished file.
- JPEG storage means the PDF isn’t a pixel-perfect copy. Keep the originals if exact values matter, as they can with measurement images.
- To turn the bitmaps into ordinary image files instead, the image converter saves BMP as JPG or PNG.
- Hundreds of large bitmaps take a lot of memory, which a computer handles more comfortably than a phone.
Conversion happens locally in your browser and no bitmap is ever uploaded; see how to check.