how to manually calculate code coverage percentage for path coverage?

I am manually creating the white-box testing for our system and I have issues with automated coverage testing tools. This is a Java-based system.

Path coverage % = (Total paths exercised / total number of paths in program) * 100

I was able to determine the total paths exercised but I don't know how to get the total number of paths in the program.

Would anyone be able to help me with this?