1) Launch Adobe Acrobat.
2) Click “File,” followed by “Open” in the main program menu and open the PDF document that you want to reduce in size.
3) Select “Choose Document” in the main menu, then click “Reduce File Size” in the drop-down menu.
4) Choose your preferred Adobe Reader version compatibility from the list of compatibility options. This controls which versions of Adobe Reader software can view the PDF file. Select compatibility for all versions of Adobe Reader if you intend to email the PDF, or distribute it on a flash drive or removable media. Web browsers automatically load the latest version of Adobe Reader, so set compatibility for just the most recent version of Adobe reader if you intend to upload the PDF to a website for online viewing.
5) Click “OK.” Type a name for the compressed PDF document into the “Name” input box. Set a computer save location for the output file. Click the “OK” button. This compresses the file and reduces the size of the PDF document.
But beware: Reducing the size of your PDF file will also reduce the resolution of graphics and images. On some photos and graphics, this might lead to slight pixelation of the image.