Images to PDF

Choosing a page size

A4 is the standard almost everywhere outside North America, and US Letter is slightly wider and shorter. If the PDF will be printed, match the paper the printer actually holds — a mismatch means either scaled-down output or clipped edges.

The "fit to image" option skips a fixed page size entirely and makes each page exactly the dimensions of its image. This is the right choice for a document meant to be read on screen, since it removes the white borders that appear when a landscape photo sits on a portrait page.

Contain versus fill

Contain scales the image until it fits inside the page with its whole area visible, leaving white space where the aspect ratios do not match. Fill scales until the page is covered and crops whatever overflows. For scanned documents, always use contain — filling will cut off the edges of the page, which is usually where signatures and page numbers live.

Getting good results from phone scans

• Shoot straight down rather than at an angle, so the page edges stay parallel.
• Use even light. A window on one side creates a bright band and a dark band that survives into the PDF.
• Keep the resolution high at capture, but consider compressing the images first if the resulting PDF needs to be emailed — a dozen full-resolution phone photos easily exceed most attachment limits.
• Convert to greyscale before building the PDF for text documents; it cuts size substantially and reads no worse.

Why file size grows quickly

A PDF built from images stores each image more or less as it arrived, plus a small amount of document structure. Ten photos of 4 MB each produce a PDF of roughly 40 MB — the format is not compressing them further. If size matters, reduce the images before conversion rather than looking for a setting here.

Frequently asked questions