Convert PNG to PDF

How this tool builds a real PDF

This isn't an image with a .pdf extension slapped on it — it's a genuine PDF document, assembled object by object:

• A real page tree — a Catalog and Pages object, with one Page object per image, each sized to that image's dimensions.
• Raw, lossless pixel data — each image's actual RGB pixels are read from the browser's own canvas, compressed with the same /FlateDecode filter PDF uses for lossless streams (the same algorithm family PNG itself uses), and embedded directly — no JPEG re-encoding, so there is zero quality loss.
• Real transparency via /SMask — when a PNG has an alpha channel, it's extracted and embedded as its own grayscale image object, referenced by the page's image as its /SMask — the PDF specification's standard soft-mask mechanism, not a flattened or simulated effect.
• A correct cross-reference table — every object's exact byte offset is recorded, the way the PDF specification requires, so any standards-compliant reader can jump straight to any page.

We verify every generated PDF independently with qpdf's structural checker, render it with Poppler's pdftoppm, and re-parse it with Python's pypdf to confirm the page count, image data and dimensions all round-trip correctly — not just that Acrobat happens not to complain.

Why convert PNG to PDF

PNGs are common for screenshots, diagrams, logos and scanned documents that need to stay perfectly crisp — exactly the cases where you don't want any JPEG-style recompression loss. Converting to PDF makes a set of PNGs easy to print, email or archive as one file, and this tool keeps every pixel and every transparent edge exactly as it was, which matters for a logo or diagram that needs to stay lossless.

Edge cases this tool handles

Transparent PNGs

If a PNG has an alpha channel, this tool extracts it and embeds it as a real PDF /SMask so the transparency still shows through on top of whatever the PDF page is laid over — it's never flattened onto a white background the way the JPG-to-PDF tool has to.

Multiple images, different sizes

Each page is sized independently to match its own image's proportions, rather than forcing every page to a fixed size and awkwardly padding or cropping smaller or differently-shaped images.

Large batches and file size

Because pixel data is stored losslessly rather than JPEG-compressed, a PNG-to-PDF file is typically larger than the equivalent JPG-to-PDF output — the tradeoff for zero quality loss. Every image is processed and embedded in your browser's memory, so very large batches of very high-resolution images will simply take longer and use more memory, rather than hitting a server-side upload limit.

Related file extensions & tools

Frequently asked questions