DETERMINING THE ALCOHOL CONTENT

A hydrometer (pictured right) measures the sugar content of various liquids, which determines the potential alcohol content. Before brewing, test a sample of your brew and write this down in your brew log. Once fermentation is complete, test a new sample and determine the difference between readings, to determine your brew’s alcohol content.
     
How to Test: Place a small amount of the test liquid into a trial jar. Lower the hydrometer slowly into the liquid, spin to remove air bubbles and allow to rest in the jar (without touching sides). Write down reading, adjusting for a lower temperature if the liquid is below/above 20°C.
   
Specific Gravity
(SG)
Sugar
per litre
(grams)
Potential Alcohol Content (%)

Specific Gravity (SG)
Sugar
per litre
(grams)
Potential Alcohol Content (%)
0.980
-
-1.9
1.065
169
8.6
0.985
-
-2.6
1.070
182
9.3
0.990
-
-1.3
1.075
195
9.9
0.995
-
-0.7
1.080
208
10.5
1.000
0
0.0
1.085
222
11.3
1.005
13
0.6
1.090
235
11.8
1.010
26
1.3
1.095
249
12.6
1.015
39
1.9
1.100
262
13.2
1.020
52
2.6
1.105
275
13.9
1.025
65
3.2
1.110
288
14.3
1.030
78
3.9
1.115
301
14.7
1.035
91
4.5
1.120
315
16.0
1.040
104
5.3
1.125
329
16.6
1.045
117
5.8
1.130
341
17.3
1.050
130
6.4
1.135
355
17.9
1.055
143
7.3
1.140
368
18.6
1.060
156
7.8
1.145
-
-

Temperature
(°C)
S.G. Adjustments
Hydrometer Example:
Initial SG (before fermentation) = 1.090 
= 11.8% ABV
Final SG (after fermentation) = 1.010 
 = 1.3% ABV
Approximate alcohol content = 11.8-1.3 
 = 10.5% ABV

Adjusting Sugar: Determine final PAC 
i.e. 5.8% = 117g sugar required per litre. 
Then test the initial sample
i.e. SG = 1.030 = 78g sugar present in the liquid. 117-78
= add 39g sugar per litre before fermentation.          
10
-0.002
15
-0.001
20
NONE
25
+0.001
30
+0.003
35
+0.004

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