How to Correct Your Hydrometer Reading for Different Sap Temperatures

by Tig Tillinghast

When you let concentrated sap cool a little bit, the hydrometer reading will be slightly off from its indicated scale. This is a table of temperatures (on the left) of the sap, and the reading you should look for (on the right) where the actual density of the sap will be Vermont’s mark for syrup, which is 67.1.

Many hydrometers are geared to give you this reading at 55 degrees Fahrenheit, and you will notice that the table below shows this temperature as the only one not requiring correction.

Temp Density


40 67.9
41 67.8
42 67.8
43 67.7
44 67.7
45 67.6
46 67.6
47 67.5
48 67.5
49 67.4
50 67.4
51 67.3
52 67.3
53 67.2
54 67.2
55 67.1
56 67.1
57 67.0
58 67.0
59 66.9
60 66.8
61 66.8
62 66.7
63 66.7
64 66.6
65 66.6
66 66.5
67 66.5
68 66.4
69 66.4
70 66.3
71 66.3
72 66.2
73 66.2
74 66.1
75 66.1
76 66.0
77 66.0
78 65.9
79 65.8
80 65.8
81 65.7
82 65.7
83 65.6
84 65.6
85 65.5
86 65.5
87 65.4
88 65.4
89 65.3

90 65.3
91 65.2
92 65.2
93 65.1
94 65.1
95 65.0
96 64.9
97 64.9
98 64.8
99 64.8
100 64.7
101 64.7
102 64.6
103 64.6
104 64.5
105 64.5
106 64.4
107 64.4
108 64.3
109 64.3
110 64.2
111 64.2
112 64.1
113 64.1
114 64.0
115 63.9
116 63.9
117 63.8
118 63.8
119 63.7
120 63.7
121 63.6
122 63.6
123 63.5
124 63.5
125 63.4
126 63.4
127 63.3
128 63.3
129 63.2
130 63.2
131 63.1
132 63.1
133 63.0
134 62.9
135 62.9
136 62.8
137 62.8
138 62.7
139 62.7

140 62.6
141 62.6
142 62.5
143 62.5
144 62.4
145 62.4
146 62.3
147 62.3
148 62.2
149 62.2
150 62.1
151 62.1
152 62.0
153 61.9
154 61.9
155 61.8
156 61.8
157 61.7
158 61.7
159 61.6
160 61.6
161 61.5
162 61.5
163 61.4
164 61.4
165 61.3
166 61.3
167 61.2
168 61.2
169 61.1
170 61.0
171 61.0
172 60.9
173 60.9
174 60.8
175 60.8
176 60.7
177 60.7
178 60.6
179 60.6
180 60.5
181 60.5
182 60.4
183 60.4
184 60.3
185 60.3
186 60.2
187 60.2
188 60.1
189 60.0

190 60.0
191 59.9
192 59.9
193 59.8
194 59.8
195 59.7
196 59.7
197 59.6
198 59.6
199 59.5
200 59.5
201 59.4
202 59.4
203 59.3
204 59.3
205 59.2
206 59.2
207 59.1
208 59.0
209 59.0
210 58.9
211 58.9
212 58.8
213 58.8
214 58.7
215 58.7
216 58.6
217 58.6
218 58.5
219 58.5
220 58.4
221 58.4
222 58.3
223 58.3
224 58.2
225 58.2