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Molecular SO2 = free SO2 / (1 + 10^(pH-1.8)). Target ≥ 0.8 mg/L for white, ≥ 0.6 mg/L for red. Enter pH and free SO2 to check if your wine is protected.
Molecular SO2 for wine stability and aging.
molSO2 = freeSO2 / (1 + 10^(pH-1.8))
| Symbol | Meaning |
|---|---|
| pH | Wine pH (e.g. 3.30) |
| freeSO2 | Free SO2 in ppm (e.g. 20) |
pH 3.30, free SO2 20 ppm -> 20 / (1 + 10^(3.30-1.8)) ≈ 0.71 mg/L molecular SO2 — just at the white wine minimum.
Continue with the ABV Calculator, Alcohol Dilution Calculator, or the Chilled Drink Calculator — or browse more brewing & drinks tools and all cooking calculators.
Molecular SO2 is the active antimicrobial form. Free SO2 is total sulfite — only the molecular fraction does the work.
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Content updated: September 2026