How much alcohol can you expect to make, knowing how much sugar you
put in ? Easy. The theoretical yield is 51.1%, but you will get less
than this, around 48% because you lose some of the sugars to
forming the small amounts of other alcohols, esters, etc
(eg 480 g (610 mL) of ethanol for every 1 kg sugar). All going well, you should be able to
capture approx 90% of this, ie 550 mL pure (100%) ethanol per kg of sugar.
So ... for say 5 kg of sugar, you
should be able to get 0.55 x 5 = 2.75 L of pure ethanol. I collect
mine at 75% strength, ie I get around 2.75 / 0.75 = 3.7 L of distillate . If you run
a pot still at 40%, this means you will get around 6.9 L of distillate.
Knowing how much alcohol is present then lets you know when
your run is about to finish.
Bakers yeast will produce a maximum of around 14% alcohol, whereas the "turbos" can
generate up to 20% alcohol. Obviously you'd use different amounts of sugar for either case.
To estimate the sugar you need, multiply the wash % alcohol by the volume and by 17 grams, eg
to make 20L at 13% you'd use 20 x 13 x 17 = 4400 g = 4.4 kg.
Glucose (dextrose) can be used instead of sugar, and is sometimes said to produce
a "cleaner" wash. You will need to use slightly more (12.5%) by weight to get the
same result as using sugar (eg use 1.25kg of glucose for every 1kg of sugar needed).