It's easy to convert images into PDF files -- whether on Windows, Mac, or directly on your mobile phone. We'll show you how it works.

Windows allows you to convert any image file with JPG, JPEG, PNG format to PDF without installing any third-party software via Windows Photos App.

Some might suggest you download an app to convert a picture to a PDF on the iPhone, but the truth is you can do it for free without any apps.

To convert a JPG file to a PDF file, simply change the file format on your computer's default photo-viewing app.