BMP is raw uncompressed pixels, which is why the files are so large. PDF is a frozen page layout with no heading structure a machine can rely on. ImageMagick sits between the two, and this page says exactly what happens to a BMP file on the way to becoming a PDF one.
What runs when a BMP file becomes PDF
ImageMagick 6.9.12, on a machine we rent and watch. Your BMP file is uploaded once, ImageMagick runs once, the PDF comes back, and neither file is kept. BMP to PDF is one of the 3649 pairs that engine was probed on with a real file, which is why it has a page here and why the pairs the probe could not prove do not.
What survives from the BMP into the PDF
The pixel dimensions of your BMP file. The PDF comes out the size the BMP went in, because nothing on this path resizes anything.
Every pixel value. BMP and PDF are both lossless, so the PDF file adds no compression artefacts that the BMP did not already have.
What BMP to PDF costs you
The chance of getting text out. The PDF you receive is one page with your BMP picture painted on it. Words inside the BMP stay pixels, and nothing reading that PDF will find them.
If a model is going to read the PDF
Worth knowing before the PDF goes anywhere near an assistant: this is the wrong direction for that. A PDF is a set of positioned glyphs, and a model has to reconstruct the reading order before it can begin. If a machine rather than a person is going to read this BMP file, convert it to Markdown instead and skip the reconstruction entirely.
BMP to PDF, measured rather than promised
Running BMP to PDF against the real engine with a real file, ImageMagick wrote 118,745 bytes of PDF in under a tenth of a second, machine otherwise idle. That is one BMP file on one day and not an average, which is why the number is given together with the file that produced it.
The BMP to PDF verdict was reached by a format signature, meaning at least four bytes unique to the format were found at the right offset. Which check was used matters, because they do not all prove the same thing, and a status code of 200 proves nothing whatsoever about whether the PDF file has anything inside it.
The same BMP file, sent somewhere else
Other outputs the probe measured out of a BMP file, so the cost of choosing PDF can be read against something. Sizes do not compare across engines, because each family was probed with its own BMP witness file.
BMP to JPG: 1,568 bytes in under a tenth of a second, verified by a format signature.
BMP to PNG: 810 bytes in under a tenth of a second, verified by a format signature.
BMP to WEBP: 370 bytes in under a tenth of a second, verified by a format signature.
BMP to GIF: 3,799 bytes in 0.1 seconds, verified by a format signature.
BMP to TIFF: 72,264 bytes in under a tenth of a second, verified by a format signature.
Other ways into PDF, and what they measured
Among the published routes into PDF, BMP is the second largest output of the 26 measured. The witness files differ, so this ranks the probe run and not your document.
GIF to PDF: 1,092,578 bytes in 0.9 seconds.
HEIF to PDF: 94,782 bytes in under a tenth of a second.
ICO to PDF: 95,344 bytes in under a tenth of a second.
DOCX to PDF: 11,917 bytes in 1.2 seconds.
DOC to PDF: 11,917 bytes in 1.1 seconds.
What we will not pretend about BMP to PDF
A BMP file over 25 MB is refused before the upload finishes rather than after it, so you do not wait for a rejection.
A BMP to PDF run that passes 30 seconds is killed, and the ImageMagick process is killed with it. A run left behind would sit on one of the machine's two cores until somebody noticed.
No text is read out of the BMP anywhere on this path. Converting a picture to PDF never turns it into words, whatever the picture happens to contain.
ImageMagick was not saturated at sixteen simultaneous conversions: it held 47.5 a second while latency moved from 0.22 s to 0.34 s, and the service memory did not move off 51 MB. That is the measured headroom behind BMP to PDF, not a marketing number.
One BMP file at a time, chosen in the browser. There is nothing else to set up and nothing else on offer.
BMP to PDF: what people ask
What actually converts my BMP file to PDF?
ImageMagick does it, 6.9.12, on a machine we rent and watch. Not a browser trick and not somebody else service: the BMP file is uploaded once, ImageMagick runs once, the PDF comes back, and neither file is kept afterwards.
How long does BMP to PDF take?
On the file the probe used, ImageMagick took under a tenth of a second and wrote 118,745 bytes of PDF. That is one real measurement on one real BMP file, not an average and not a promise about yours: a larger BMP takes longer, and past 30 seconds the run is stopped.
What do I lose going from BMP to PDF?
The one to know about first: The chance of getting text out. The PDF you receive is one page with your BMP picture painted on it. Words inside the BMP stay pixels, and nothing reading that PDF will find them.
Can I put several BMP files into one PDF?
No. One BMP file goes in and one PDF comes out, with that picture on it. Nothing here merges files, orders them or numbers pages: it is one upload, one conversion, one download, and that is the whole of what this page does.
Is BMP to PDF free?
There is a free allowance every month, and one BMP to PDF conversion costs half a credit against it. When the allowance runs out the tool says so and stops, rather than quietly handing you a worse PDF.