Why convert PNG files to PDF
PNG is the usual format for screenshots, charts, diagrams, logos and designs with sharp edges and text. When you need to hand in screenshots as proof, share a design with a client or attach a chart to an application, a PDF is easier to send, print and keep together than a folder of separate PNG files.
What happens when you convert
Each PNG becomes a page in the PDF. If the PNG has transparent areas, they stay transparent in the PDF; otherwise the picture is stored in high quality. “Fit to image” keeps the page exactly the size of the picture, which is ideal for screenshots; A4 or US Letter centres the picture on a standard page with a small margin, and wide pictures get landscape pages.
Which PNG files work best
Screenshots at their original size stay perfectly readable, because PNG does not blur text. Very large PNG files — for example full-page screenshots of long websites — make tall pages; for printing, choose A4 so they are scaled to fit. Keep each picture's important content away from the edges if you plan to print.
Common problems and how to fix them
The PDF is very large: PNG photos are heavy, so convert photos with JPG to PDF instead, or compress the result with Compress PDF. A screenshot is too long for one printed page: split it into parts with Crop Image first. Pictures are in the wrong order: drag them in the list before converting.
Good habits
Use PNG for anything with text or sharp lines and JPG for camera photos, combine related screenshots into one PDF, and give each file a clear name before sharing.