You don't have to calculate that much, as long as your coin shows that you've got more than the capital that you have traded on it, then that only indicates that you're in profit.
There's no need for any complicated stuff.
To expect bigger profit then I believe you have to be a patient holder who will probably never be affected by FUD or price fluctuation. Even this method can take years, but I'm sure the risk and profit will be worth it.
That's what happened to me when I've bought some coins during their lowest and held it and sold at the mid of this bull run. Didn't maximized the profit but at least I still got more than 100% profit from those.