How to Convert a Bitmap (BMP) to PDF

BMP to PDF: the steps

1. 1

   Select your bitmaps

   Open BMP to PDF and drag files onto Select BMP images. Both .bmp and .dib files are accepted.

2. 2

   Order the pages

   Each bitmap appears as a card with its file size and pixel dimensions. Use Up and Down to change the order.

3. 3

   Choose the layout

   Pick Page size (A4, Letter or Fit to image), Orientation, Margin and Image placement. Page background appears too; leave it on None (keep transparency) unless your bitmap has transparent pixels.

4. 4

   Convert and save

   Click Convert image to PDF and then Download PDF.

Why the PDF is much smaller than the BMP

BMP usually stores every pixel uncompressed. A 1920 × 1080 screenshot is about 6 MB as a 24-bit bitmap. In the PDF, the tool stores the image as a JPEG at 92% quality, which typically takes a small fraction of that. A bitmap with real transparency (some 32-bit BMPs have an alpha channel) is stored as a lossless PNG instead, so the see-through areas survive.

For photos and scans, the 92% JPEG looks identical to the original. For pixel art, icons or screenshots with tiny text, you might see faint artefacts around sharp edges at high zoom. If that matters, save the bitmap as PNG in your image editor first and use PNG to PDF, which keeps PNGs lossless.

Large bitmaps and the 25 MB limit

Because bitmaps are uncompressed, they hit the 25 MB per-file limit sooner than other formats. A 24-bit BMP reaches 25 MB at roughly 8 megapixels, such as 3400 × 2400 pixels. If a file is rejected with "exceeds the 25 MB per-image limit", open it in Paint or another editor and save it as PNG or JPG, which shrinks it a lot, then convert that file instead.

Convert a bitmap to PDF in Windows Paint

Paint can't save as PDF directly, but it can print to one. Open the BMP in Paint, choose File > Print, and select Microsoft Print to PDF as the printer. This handles one image at a time and uses the printer's page margins. To combine many bitmaps into one PDF, or to control margins and fit, the BMP to PDF tool is quicker.

Where bitmaps come from, and what to do next

• Old scanner software and fax utilities often save BMP by default. Once converted, number the pages with Add Page Numbers.
• Industrial and lab equipment frequently exports BMP screenshots. Combine a day's captures into one report, then merge it with other documents.
• Legacy Windows apps copy screen captures as bitmaps. If the PDF is still too large to share, compress it.

Frequently asked questions