Portable Document Format, or PDF for short, is one of the most ubiquitous file formats that is universally adopted across platforms. However, they can be quite big. Thankfully, you can reduce the file size of a PDF in macOS High Sierra. Here’s how:
- Open the PDF file that you want to reduce in size. Double click it and it should open in Preview, the default PDF viewer in macOS.
- Pull down the File menu and select Export.
- Choose the submenu next to “Quartz Filter” and choose “Reduce File Size.”
- Save the new reduced version of the PDF as usual by hitting “Save."
(This how-to is based on my experiences and info on Apple's support pages — where the images sometimes come from.)