Convert PNG to PDF
Put screenshots, diagrams, scanned forms and other PNG images into one PDF, one image per page. PNG files go into the PDF without losing detail, and transparent backgrounds stay transparent. It all happens in your browser, so nothing is uploaded.
How to convert PNG to PDF
What happens to transparency when a PNG becomes a PDF
PNG is the format for images with see-through parts: logos, icons, a signature on a clear background, diagrams exported from a design app. When a PNG goes into a PDF here, its transparency goes with it. The image is placed on the page as it is, and the see-through parts are stored as see-through instead of being painted a color first.
A PDF page has no background color of its own, so what shows behind those parts depends on the program. Most PDF viewers show the page as white, so a logo on a clear background looks the way it would on a white web page, and a printer leaves those areas as blank paper. A white logo made for dark backgrounds will be hard to see on a white page, so open the PDF and check it before you send it.
There is one exception. If a PNG uses an unusual variant that cannot be placed as it is, it is saved as a JPEG instead and its see-through parts become white. The same happens to WebP images with transparency, which are always saved as JPEG inside the PDF.
Screenshots and graphics in one PDF
Screenshots are the most common reason to turn PNG into PDF: a chat to keep as a record, the steps of a bug report, an order confirmation, a web page that may change tomorrow. Drop them all at once and each screenshot becomes its own page in a single PDF, which is easier to attach, print or file away than a folder of loose images.
Because PNG images go in without lossy compression, text in a screenshot stays as crisp as it was on your screen, and the lines and flat colors of charts and diagrams do not pick up the blurry edges that JPEG compression can add. The image is not resized either, so zooming in on the PDF shows the same detail as zooming in on the original file.
Pages follow the order in which the files arrive, and the tool cannot reorder them afterwards, so number the file names if the order matters. Several images give one file called squishly-images.pdf, and a single image gives a PDF with the same name as the picture.
Page size for PNG images
Fit image is usually the best choice for screenshots. Each page takes the shape of its image, with no margin, so a tall phone screenshot becomes a tall, narrow page and a wide desktop screenshot a wide one. The long side of every page is the length of the long side of an A4 sheet, which keeps the pages a similar size as you scroll through the PDF.
Choose A4 or Letter when the PDF will be printed or a form asks for a standard page. Each image is scaled to fit inside a 1 cm margin and centered, and an image that is wider than it is tall gets a landscape page. With every page size, small images are scaled up to fill the page, so a tiny icon on its own page will look large and soft. Export small graphics at a bigger size before you convert them.
PNG files from screenshots and design apps can be large, and they go into the PDF at their full size. If the PDF has to be small, compress PNG makes the images lighter before you convert them, and compress PDF works on the finished file.