What this calculator does
Molecular SO2 in wine works out the antimicrobially active molecular SO2 fraction, from free SO2 and wine pH. Enter your own figures above and the answer updates as you type: nothing is fixed in the code, so the result reflects exactly the numbers you supply.
The formula this calculator evaluates is printed under the tool and explained below, so you can check the working by hand or reuse it in a spreadsheet.
The formula
FormulaMolecular SO2 = free SO2 / (1 + 10^(pH − 1.81)), where 1.81 is the pKa of SO2 in wine
The inputs explained
| Field | What to enter |
|---|---|
| Free SO2 (mg/L (ppm)) | A number, measured in mg/L (ppm). Starts at 30. |
| Wine pH | A number. Starts at 3.4. |
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the answer changes with free so2
Every other input is held at the calculator’s starting values while free so2 varies. Select any row to load that scenario into the calculator.