BMP to PDF Converter

1. Choose your BMP files, or drop them onto the box. They are opened in your browser, so nothing leaves your device.
2. Put them in order with the arrows. Each image becomes one page, top of the list first.
3. Pick a page size. Same as image makes each page exactly fit its picture; A4 or Letter gives a printable page.
4. Check the preview, then click Convert to PDF and download.

The pictures go into the PDF without any loss of quality, pixel for pixel. If the file comes out too big, tick Smaller file and convert again (see below). PNG and JPG images can go in the same PDF too.

BMP (bitmap) is the old Windows image format used by Paint, scanners and some screenshot tools. It stores every pixel without compression, so the files are very large, and some phones, websites and email services won't open or accept them.

• It opens anywhere. Every phone, computer and browser can show a PDF, and it looks the same on all of them.
• Several images, one file. A batch of scanned pages becomes a single document instead of a folder of loose pictures.
• It prints at a real page size. A PDF page can be A4 or Letter, so the printout comes out the size you expect.
• Forms and portals accept it. Job applications, schools and government sites usually ask for PDF, not BMP.

Almost always, because the PDF stores the picture compressed and the BMP does not. A normal 24-bit BMP takes 3 bytes per pixel, so its size is simply width × height × 3. A 1920 × 1080 screenshot is 1920 × 1080 × 3 = 6,220,800 bytes, which Windows shows as 5.9 MB, however simple the picture is.

How much smaller the PDF gets depends on the picture. Screenshots, diagrams and scanned text have large areas of flat colour and usually shrink to a small fraction of the BMP with no loss at all. Photos have detail in every pixel and shrink less. For photos, tick Smaller file: images are stored as JPG instead, which typically makes a photo PDF around a tenth of the BMP's size with no difference you'd notice on screen. If a finished PDF is still too large, Compress PDF can shrink it further.

Select all the BMPs at once, or add them a few at a time with Add more images. Each one becomes a page in the order of the list. Click a file to preview its page and use the arrows to move it.

Need a separate PDF for each picture instead? Tick One PDF per image under Fine-tune and you get a ZIP with one PDF per BMP, each named after its image. To number the pages of the finished PDF, use Add page numbers to PDF.

With Same as image, the page size comes from the resolution saved in the BMP. A page scanned at 300 dpi comes out as a real A4 or Letter page. When the file has no resolution saved, 96 dpi is used, so a 1920 × 1080 screenshot makes a 20 × 11.25 inch page; PDF readers shrink it to fit the screen.

On paper sizes, Fit shows the whole picture and leaves a border where the shapes differ. Fill covers the page and trims whatever sticks out. Pages turn to landscape for wide images unless you choose otherwise under Fine-tune. Add a small margin if you'll print; most printers can't print right to the edge.

• Small images look soft when printed. A 640 × 480 picture stretched across an A4 page works out at under 80 dpi. Use Same as image, or start from a bigger image, if it needs to look sharp.
• Text in the picture isn't searchable. The PDF holds a picture of the page, so you can't select or search its words.
• A few rare BMP types won't open. If a file can't be read, open it in Paint or another editor, save it again as a 24-bit BMP or PNG, and add that instead.
• Very large images on phones. iPhones and iPads limit the size of image a web page can handle, so pictures over about 16 megapixels are scaled down to fit, and the tool tells you when that happens. A computer keeps them at full size.
• Transparent areas take the background colour set under Fine-tune, white by default.

Converting WebP pictures instead? Use WEBP to PDF.