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ImageConverter

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BMP to PDF Converter

Convert a BMP image into a PDF document. Unusually for a format conversion, the result is normally smaller than what you started with — around 30% smaller in testing — while keeping every pixel exactly. The reason is that BMP barely compresses at all.

Deleted automatically Uploads removed within 30 minutes

Drag and drop your BMP images here

Add several at once. Each file is processed and then deleted from our server.

Up to 20 MB per file Batch ready

Step by step

How to convert BMP to PDF in 3 steps

  1. Add your BMP file

    They are large, so the upload may take a moment.

  2. Nothing to configure

    The conversion is lossless in both directions.

  3. Download your PDF

Format comparison

BMP vs PDF

BMP (Windows Bitmap)

Uncompressed

An early Windows format that stores pixels more or less raw, with little or no compression.

  • Read by old and embedded software that knows nothing newer
  • No compression artefacts
  • Very large files for the image size

PDF (Portable Document Format)

Document

A fixed-layout document format that looks the same on every device and printer.

  • Opens identically everywhere, and prints reliably
  • Holds many images as pages of one file
  • A document rather than an image, so it is awkward to edit or embed

Why the document is smaller than the image

BMP is the oldest format on this site and the simplest. It stores each pixel as a plain run of bytes with, in almost every file you will encounter, no compression whatsoever. A 1200 × 800 photograph is about 2.9 MB regardless of what it contains — a blank white rectangle occupies exactly as much space as a detailed landscape.

A PDF will not do that. When it stores an image it has no native codec for, it applies Flate — the same lossless compression PNG uses. Flate is not especially clever on photographs, but compared with nothing at all it is a substantial improvement.

Measured: a 2.88 MB BMP became a 2.02 MB PDF. Every pixel identical, roughly 30% saved, purely because the source was storing them so wastefully.

On a screenshot, a diagram or line art the saving is far larger — flat areas of identical colour are exactly what Flate handles best, and reductions of 80% or more are ordinary.

Nothing is lost

Flate is lossless. The pixels in the document are bit-for-bit the pixels in the BMP: no re-encoding, no quality setting, no generation lost. This is one of the rare conversions where "smaller" and "identical" are both true.

If you want it smaller still

For a photographic BMP, converting to JPG first and then to PDF produces a dramatically smaller document again — JPEG data is embedded untouched, and JPEG is enormously more efficient on photographs than Flate. The cost is one round of lossy compression, invisible at a high quality.

For screenshots and diagrams, stay lossless. JPEG smears exactly the hard edges those are made of.

Quality

Quality and file size

There is no quality setting, because nothing is discarded at any point.

Where BMP files come from

Almost always Windows, and usually older Windows. Classic Paint saved BMP by default, scanner software of a certain age produced it, and some industrial and medical equipment still writes it because the format is trivial to implement.

Those origins are worth knowing because they predict the content: BMPs are far more often screenshots, scans and diagrams than they are photographs, and that is the case where this conversion shines.

Transparency

BMP has no usable transparency in practice, so there is nothing to lose. Whatever the image shows is what the page shows.

Colour depth

Older BMPs are sometimes 8-bit or even 4-bit — 256 or 16 colours. Those convert perfectly well and produce very small documents, since a limited palette compresses beautifully. The image will not gain colours it never had, but nothing is lost either.

Print size

Converting does not change the pixel count, and the pixel count decides how the document prints. For a full page at print quality, aim for about 2480 × 3508 pixels on A4.

Why convert BMP to PDF at all

  • BMP is awkward to share. It is large, and plenty of software and web forms will not accept it.
  • The upload only accepts PDF, which is a large share of the reason anyone converts anything.
  • It needs to be printed, and PDF prints predictably.
  • It is going into a document with other pages.
  • The file needs to shrink without losing anything — which, unusually, this conversion achieves on its own.

Old files, and what to expect

BMPs tend to be old, and old files come with quirks. Some use bottom-up row order, some carry unusual colour depths, a few use the rare RLE compression. All of these convert without fuss.

If a very old BMP will not convert, it is most likely one of the genuinely obscure variants — 16-bit colour with unusual channel masks, or an OS/2 header. Opening it in any modern image editor and saving it as PNG first will normalise it.

Several images into one document

This makes one PDF from one image. For a multi-page document, images to PDF takes up to fifty files with drag-to-reorder and one page each.

Text stays a picture

A scanned page converted to PDF is a picture of a page. It cannot be searched, selected or copied from — that needs optical character recognition, which is a different tool. Worth knowing before submitting one somewhere that expects searchable text.

What happens to your file

Browsers cannot write PDF documents, so this runs on our server. Your upload is deleted the moment conversion finishes, the result is deleted as you download it, and anything abandoned is swept automatically. BMPs are large; nothing is kept a second longer for it.

Privacy

What happens to your file

This tool runs on our server, so it works the same on every phone and computer. Your file is uploaded, and this is exactly what happens to it:

  • Stored outside the public web root under a random name, never under your file's name.
  • Processed, with the original upload deleted immediately — whether it succeeded or failed.
  • The result sits behind a signed link that only you receive, which stops working after 20 minutes, and the file is deleted the moment you download it.
  • Anything never collected is deleted automatically within 30 minutes.
  • The image itself is never logged or kept. If a conversion fails, we record the formats involved and the error — not the file.
  • Camera metadata, including any GPS coordinates recording where a photo was taken, is removed from the result. Only the rotation needed to show the image the right way up is kept.

Questions & answers

BMP to PDF: frequently asked questions

Why is the PDF smaller than my BMP?

Because BMP stores pixels with no compression at all — a 1200 × 800 image is about 2.9 MB whatever it contains — while a PDF applies lossless Flate compression. Measured, a 2.88 MB BMP became a 2.02 MB PDF with every pixel identical. On screenshots and diagrams the saving is far larger, often over 80%.

Does anything get lost?

No. Flate is lossless, so the pixels in the document are bit-for-bit the pixels in the BMP. This is one of the rare conversions where the result is both smaller and identical.

How do I make it smaller still?

For a photograph, convert to JPG first and then to PDF — JPEG data is embedded untouched and is far more efficient than Flate on photographic content. For screenshots and diagrams, stay lossless: JPEG smears exactly the hard edges those are made of.

My BMP is very old and will not convert. Why?

Probably an obscure variant — 16-bit colour with unusual channel masks, or an OS/2 header. Bottom-up row order, low colour depths and RLE compression are all handled. Opening it in any modern editor and saving as PNG first will normalise it.

Will a 256-colour BMP convert properly?

Yes, and it will produce a very small document, because a limited palette compresses beautifully. The image will not gain colours it never had, but nothing is lost either.

Can I combine several BMPs into one PDF?

Not with this tool, which makes one document per image. The images-to-PDF tool takes up to fifty files, lets you drag them into page order, and gives each its own page.

Keep going

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