SULPHUR DIOXIDE ADDITIONS using POTASSIUM METABISULPHITE.

The TABLE gives the volume in mL of 10% Potassium metabisulphite solution to add a desired amount of  Sulphur dioxide to a known volume of must or wine.
Volume in litres 0.75 1.00 4.55 19.1 22.7 25.9 27.3 54.0 114 150 182 227
Volume in                        
imperial gallons 0.17 0.22 1.00 4.2 5.0 5.7 6.0 11.9 25 33 40 50
Parts per million                        
S02 desired  

  mL   of  10  %  Potassium metabisulphite  solution  to add:  
milligrams/litre                        
10 0.13 0.18 0.80 3.35 3.99 4.55 4.78 9.47 19.9 26.3 31.9 39.9
20 0.26 0.35 1.59 6.70 7.97 9.09 9.57 18.9 39.9 52.6 63.8 79.7
30 0.39 0.53 2.39 10.0 12.0 13.6 14.4 28.4 59.8 78.9 95.7 120
40 0.53 0.70 3.19 13.4 15.9 18.2 19.1 37.9 79.7 105 128 159
50 0.66 0.88 3.99 16.7 19.9 22.7 23.9 47.4 100 132 159 199
60 0.79 1.05 4.78 20.1 23.9 27.3 28.7 56.8 120 158 191 239
70 0.92 1.23 5.58 23.4 27.9 31.8 33.5 66.3 140 184 223 279
80 1.05 1.40 6.38 26.8 31.9 36.4 38.3 75.8 159 211 255 319
90 1.18 1.58 7.18 30.1 35.9 40.9 43.1 85.3 179 237 287 359
100 1.32 1.75 7.97 33.5 39.9 45.5 47.8 94.7 199 263 319 399
  

The solution is made adding sufficient water to 100 g of Potassium metabisulphite  to bring the total volume to 1000 mL.

Figures are based on 4.545 L/imperial gallon & 10% "Sulphite solution" being 5.7%  available SO2 in mg/L

It should be noted that when you add Sulphur dioxide to a must or wine, it will not all remain as free. Depending on how much has been added previously, more or less of it will immediately become bound.
This table should be used in conjunction with the article entitled:

The Use of Sulphur Dioxide in Winemaking
 © Charles Plant 2001