Convert PNG to PDF — lossless, with transparency handled properly
The PNG to PDF converter combines one or more PNG images into a single PDF document. PNG is a lossless format, and this tool keeps it that way: the pixels go into the PDF with lossless compression, so diagrams, charts, scanned forms, design exports and screenshots stay exactly as sharp as the originals.
It also deals with the part that trips up many converters — transparency. A logo or illustration with a see-through background can turn up with a black or grey box behind it in some PDF viewers, print drivers and older programs. Here you choose what transparent areas become: white, any colour you pick, or genuinely transparent if you know your reader handles it.
Everything is built inside your browser with the open-source pdf-lib library. Your images are never uploaded, so certificates, ID scans and client artwork stay on your device.
How to convert PNG to PDF
- Drop your PNG files onto the box above, click it to choose them, or paste a copied image with Ctrl+V.
- Put the pages in order: drag thumbnails on a computer, use the arrow buttons on a phone, or press “Sort by name”. Images with transparency are labelled “transparent”.
- Choose the page size (A4, US Letter or Fit to image), orientation and margin.
- Under “Transparent areas”, keep “Flatten onto white”, pick another colour, or choose “Keep transparent”.
- Press “Convert to PDF”. The file png-images.pdf downloads, and you can save it again with the Download button.
PNG to PDF features
Lossless embedding
PNG pixels are stored with lossless Flate compression — no JPEG step, so text and fine lines never blur.
Correct transparency
Transparent pixels are flattened onto the colour you choose, so the page looks the same in every viewer and on paper.
Transparency detection
Each thumbnail shows whether the PNG really contains see-through pixels, so you know which pages are affected.
Page layout options
A4, US Letter or a page exactly the size of each image at 96 pixels per inch, with automatic portrait or landscape and three margin sizes.
Reorder and remove
Drag-and-drop, arrow buttons, natural sorting by file name and one-tap removal.
Why transparent PNGs sometimes print with a black background
A PDF stores a transparent image as two parts: the colour pixels and a separate “soft mask” that says how opaque each pixel is. Transparent pixels still have a colour underneath, and many design programs save that hidden colour as black. Modern viewers apply the mask and you never see it, but some older viewers, print drivers, fax and document-management systems ignore the mask — and the hidden black appears.
Flattening avoids the problem completely: each transparent pixel is blended with the background colour before it goes into the PDF, so there is nothing left to misinterpret. Use “Keep transparent” only when the PDF will be placed on top of something else, for example in a layout program.
Which page size should you pick?
| Option | Result | Good for |
|---|---|---|
| A4 | 210 × 297 mm, image scaled to fit inside the margin | Printing and forms in India, the UK, Europe and most countries |
| US Letter | 8.5 × 11 in, image scaled to fit | Printing in the US and Canada |
| Fit to image | Page = image size at 96 px per inch, plus any margin | On-screen reading, slides, design proofs |
Good to know
- The PDF can be larger than the PNG files, because PNG uses extra filtering tricks that PDF image compression does not. If size matters, shrink the finished file with Compress PDF.
- 16-bit PNGs are stored at 8 bits per channel, which looks identical on screen and in print.
- Animated PNGs (APNG) are added as their first frame.
- Have photos as JPG? JPG to PDF keeps JPEGs without re-compression. Need a PNG of a PDF page instead? Use PDF to PNG.
PNG to PDF FAQ
How do I convert PNG to PDF for free?
Add your PNG images above, arrange them and press “Convert to PDF”. It is free, needs no account and adds no watermark.
Does converting PNG to PDF reduce quality?
No. The images are stored losslessly, so every pixel is kept. Only 16-bit PNGs are reduced to 8 bits per channel, which is not visible.
How do I keep a transparent PNG from getting a black background in the PDF?
Leave “Transparent areas” on “Flatten onto white” (or choose a colour). The transparency is blended in before saving, so no viewer or printer can show a black box.
Can I combine multiple PNG files into one PDF?
Yes. Add as many PNGs as you like; each becomes a page in the order shown. Use the arrows or drag thumbnails to change the order.
Are my images uploaded?
No. The PDF is created in your browser and your files never leave your device.
Can I paste a PNG instead of choosing a file?
Yes — copy an image and press Ctrl+V (⌘V on a Mac) on this page. For a paste-first workflow with automatic cropping, try Screenshot to PDF.