I personally don't make starters from yeast stored a relatively short while, and if it's been long enough that I'm worried, I just buy fresh since I'm not using any rare unicorn yeasts. (I can't really quantify the time limits, but a few weeks is surely nothing to worry about.) I also don't use calculators for any pitch rates. I generally think that unless you're doing actual cell counts you're in the dark, calculators are just WAGs, and cell counts aren't that important anyway. (S. cerevisiae posted way back when about the number of minutes difference in lag time doubling or halving cell count makes. Minutes, like maybe 60-90.) I have just developed an approach based on how much slurry I generally pitch, and I adjust that (just pitch more slurry) to account for higher gravity, lower temperature (lagers pitched cold,) yeast that's been stored long enough to lose some viability, a jar with extra trub, and such. It may not be scientific, but it allows consistency and it works. (Maybe that means it IS scientific...) I'm sure others have completely different methods.