Firstly, you should choose the diagram software which supports the file formats conversion and run it.
Click Open to Open a Flowchart
Go to File→Export & Send, select PDF,PS,EPS→PDF Vector Format.
Browse your computer and choose a location to save your PDF file.
Then you get your flowchart successfully converted to PDF with just several clicks. Below is a converted PDF example. Isn't it very easy and fast?
The creator of this guide has not included tools