The Compleat Distiller

THE COMPLEAT DISTILLER 15
Most home brewers or wine makers have a hydrometer to measure sugar content in their wort or must.
Many of these hydrometers have several different scales on them. There are many possible scales for
measuring the density (and hence, the sugar content) of a solution. The most common include:
Specific Gravity and degrees Plato, Brix or Ballings.
The specific gravity of a solution is the ratio of its density to that of pure water. A specific gravity of
1.050, for example is 5 % denser than pure water. The Plato, Brix and Ballings scales all relate the
density of the solution to the % sucrose by weight. Sucrose (common table sugar) was chosen because
it is the sugar that dissolves in water to produce the greatest density. Appendix 3 includes a table that
shows the relationship between sugar content and several common hydrometer scales.
Fortunately, we do not need a hydrometer to make up a correct sugar solution for fermentation. All we
need to do is calculate the grams per liter of sugar we want from the % alcohol we’re trying to reach
using the following equation:
• % alcohol desired x 17 = grams of sugar per liter of solution
Then, calculate the weight of sugar needed based on the g/l sucrose desired, using one of these
equations:
• Metric units: g/l sucrose desired x liters desired ÷ 1000 = kg sugar
• American units: g/l sucrose desired x US gallons desired ÷ 120 = lb. sugar
• Imperial units: g/l sucrose desired x Imperial gallons desired ÷ 100 = lb. sugar
BE CAREFUL! You are after g/l of sugar in the final solution, so weigh out the sugar and slowly add
enough water to end up at your final amount of liquid! If you add the sugar to the measured amount of
water, you will end up with more liquid that is less concentrated than you expected. If you use some
sugar other than sucrose, you can dissolve the proper grams into the correct final volume, but the
specific gravity or degrees Plato measured with a hydrometer will mislead you.
Here are some sample calculations to show the various ways these equations can be used:
• We want to end up with 9 US gallons of 20 % alcohol. How much sugar do we need?
20 % alcohol x 17 = 340 g/l sugar.
340 g/l sugar x 9 gallons ÷ 120 = 25.5lb sugar
• We have a 25 pound sack of sugar. How much 15 % ethanol can we make?
15 % alcohol x 17 = 255 g/l sucrose
(now, turn the equation around. Volume x g/l ÷ factor = Weight Sugar, which means that
Volume = Weight sugar ÷ g/l sugar x factor. We’ll work this all three ways.)
Metric:
American:
Imperial:
11.34 kg ÷ 255 g/l sugar x 1000 = 44.5 liters
25 lb ÷ 255 g/l sugar x 120 = 11.76 US gallons
25 lb ÷255 g/l sugar x 100 = 9.8 Imp. Gallons
(As a practical matter, rounding to the nearest quart or liter is just fine)