Although this is a very handy Excel spreadsheet, I have it and use it from time to time and I have thanked the writer for his work and making it available, there is a website that does the same thing and more. The web page calculator even does dual and quad coil calculations.
Steam Engine | free vaping calculators
So check that out if you are dripping and or use multiple coils in your atomizers.
i have used that one until this point. this one is easier for me to use at work so im not online that much trying to come up with my next build.