Convert images to PDF

Why put images into a PDF at all

A PDF is a container that keeps pages in order, opens on every device, prints predictably and can be attached to an email as a single file. That makes it the natural home for a batch of phone photos of a paper form, a set of receipts for an expense claim, a scanned ID, a series of screenshots documenting a problem, or a portfolio of artwork. Sending six JPGs is messy; sending one six-page PDF is not.

How the pages are built

Each image becomes one page. The page size is set from the options above: either the image's own pixel dimensions, so nothing is scaled, or a standard paper size such as A4 or US Letter with the image fitted inside and centred. Fitting to a paper size is the right choice for anything that will be printed or read as a document. Using the image's own size is better for photographs and artwork where you want every pixel preserved and no white borders.

Images are embedded in their original encoding where possible. A JPG stays a JPG inside the PDF, so the PDF ends up roughly the sum of the image sizes plus a little overhead. PNG images with transparency are placed on a white page background.

Page order

Pages follow the order the files are listed in the tool. Most browsers list dropped files in the order you selected them, which for a folder is usually alphabetical. If you need a specific sequence, name the files with a leading number (01, 02, 03) before dropping them in, or drop them one at a time in the order you want. The batch rename tool can add numbering in one step.

Keeping the PDF a sensible size

Phone photos are typically 3 to 6 MB each, so a twenty-page PDF of raw photos can easily be 80 MB, which will bounce from most email systems. Two options:

• Run the images through the image compressor first with a max width of around 1,600 px and quality 80. Twenty pages will then be around 5 MB.
• Build the PDF at full size and then run it through the PDF compressor, which re-renders the pages at a smaller size.

For documents that need to remain legible when printed, 1,600 to 2,000 pixels on the long edge is plenty. For photographs meant to be viewed on screen, 1,200 px is enough.

Typical uses

Because the PDF is assembled in your browser, IDs, contracts and financial documents never leave your device.