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
|