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.

Other ways to turn PNGs into a PDF

Mac: Finder's Create PDF quick action

Select the PNGs in Finder, Control-click (right-click) the selection and choose Quick Actions > Create PDF. macOS saves a single multi-page PDF next to the originals, with pages in the order the files are sorted in that Finder window — rename them with numbers first (01-login.png, 02-settings.png) if order matters. Preview works too: open the images together, arrange the sidebar thumbnails, and use File > Print > PDF > Save as PDF.

Any computer or Chromebook: print from Chrome

Drag a PNG into an empty Chrome tab, press Ctrl+P (Command-P on a Mac), set Destination to Save as PDF and open More settings to choose the paper size, margins and scale. It's the quickest way to get a single screenshot onto a standard Letter or A4 page with white margins, which this converter doesn't do. On Windows, the Microsoft Print to PDF route described on the JPG to PDF page works for PNGs too.

Print-based methods are built for paper, so they generally place the image on a white page; if you need the transparent areas to stay transparent, use this converter instead.

Command line

img2pdf diagram-1.png diagram-2.png -o diagrams.pdf keeps PNGs lossless, and current versions store transparency as a soft mask just as this tool does. With ImageMagick, add -compress Zip — magick diagram-1.png diagram-2.png -compress Zip diagrams.pdf — so the images are stored losslessly rather than recompressed.

Screenshots, scans and searchable text

Page size

Pages are sized at 96 pixels per inch, so a 1920×1080 screenshot becomes a 20 × 11.25-inch page and a tall phone screenshot becomes a long, narrow page. PDF readers fit pages to the window, and print dialogs shrink them with Fit. The tool ignores any DPI setting stored in the PNG, which is why a Retina Mac screenshot comes out larger here than in apps that honor that setting — the pixels, and the sharpness, are identical.

File size

Flat-color images — screenshots, charts, line diagrams — compress very well. Photos and color scans saved as PNG don't, and the PDF can come out larger than the PNG files themselves, because this tool stores the plain pixel data instead of using PNG's own row-by-row prediction tricks. For photographic content, convert with JPG to PDF instead (turn the images into JPGs first with PNG to JPG) for a far smaller file.

Making the text searchable

A PDF built from screenshots or scans holds pictures of text, not text: you can't select, search or copy it, and screen readers can't read it. Running OCR (optical character recognition) adds an invisible text layer. Adobe Acrobat's Scan & OCR tool does this, as does the free command-line tool ocrmypdf diagrams.pdf diagrams-searchable.pdf. To check whether a PDF already has real text, open it in our PDF viewer, which shows any text it can extract.

Related file extensions & tools

Frequently asked questions