How do I calculate attenuation?

Ingredients
1

I apologize if this has been asked before, or if this is a ‘stupid’ question, but how does one figure attenuation of yeast?

Safale 04 has Min Attenuation 72% and a Max Attenuation 75%
If the SG is 1.066, how do I figure FG? I know the answer is right in front of me but I just cannot grasp it.

2

Final Gravity = 1 + ((Total Gravity Points * (1 - Attenuation Percent)) / 1000)

1+((66*(1-.72))/1000) = 1.01848
1+((66*(1-.75))/1000) = 1.0165

3

OP - Keep in mind that your attenuation may well NOT lie in between those minimum and maximum attenuation numbers. And if so, that doesn’t mean you did anything wrong -they are rough guidelines at best that don’t take into account your mash temp(s), grist, yeast health/viability, pitching rates, aeration at pitching, etc. I often exceed stated attenuation ranges depending on what I’m brewing.

4

Thanks for the help! This will also be useful when using Brulosophy’s Lager method.