Yeast growth factor?

I am sorta crash coursing myself on yeast pitching calculators, I have gotten a few recommendations for yeastcalc.com. That being said, my home desktop has died, and I am currently an iPhone/iPad only household. Also known as 'no flash' which yeastcalc requires. So I bought the mrmalty app, i like it, but there is an option at the end for setting growth factor. It's set at 3.00. I understand what growth factor means, but have no clue how to determine if 3.00 is the correct rate for me. Any insight?