Alcohol by Spirit Indication
Details: This calculator will calculate alcohol by volume from the spirit indication procedure. This procedure involves taking a sample of known volume and making a hydrometer reading. The sample is then boiled until it is reduced to about half its initial volume, topped up to the initial volume again with distilled water (or any water giving a hydrometer reading of 0.000), and a final reading is taken.
This calculator includes hydrometer temperature correction so it is not essential to ensure the initial and final readings are made at the same temperature, however the temperatures, and calibration temperature of the hydrometer must be known.
Note: This procedure, if performed carefully, will provide accurate results in wines regardless of residual sugar.
This calculator uses the same logic as in the 'Hydrometer Temperature Correction' calculator for correcting the readings for the temperatures at which they were taken. The difference between the initial and final gravities is then used to calculate the alcohol using the following formula:
alc = 0.008032927443 * si2 + 0.6398537044 * si - 0.001184667159
si = spirit indication (the difference between the gravities * 1000)
VinoCalc by Jonathan Musther - firstname.lastname@example.org