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Calcimator

Sulfite Addition Calculator

Calculate grams of potassium metabisulfite (KMS) needed to raise free SO2 to target levels, accounting for wine volume and pH for proper antimicrobial protection.

Inputs

gal
ppm
ppm

Results

Potassium Metabisulfite

7.89 grams

Antimicrobial Protection

Yes (≥0.5 ppm molecular)

KMS (teaspoons)1.38 tsp
Campden Tablets17.9 tablets
SO₂ Increase Needed20 ppm
Molecular SO₂ at Target0.88 ppm
How to Use This Calculator
  1. Enter Wine Volume, Current Free SO₂, and Target Free SO₂.
  2. Set Wine pH.
  3. Review Potassium Metabisulfite (grams) and Antimicrobial Protection.
  4. Use KMS (teaspoons) (tsp) and Campden Tablets (tablets) to inform your decision.
  5. Use the chart to visualize the results and explore different scenarios by adjusting inputs.

How the result changes with Target Free SO₂

Target Free SO₂Potassium MetabisulfiteAntimicrobial Protection
191.58 gramsNo (below 0.5 ppm molecular)
4210.65 gramsYes (≥0.5 ppm molecular)
6921.29 gramsYes (≥0.5 ppm molecular)
9129.97 gramsYes (≥0.5 ppm molecular)

What each input means

Wine Volume
Total volume of wine to treat in US gallons. A standard barrel is 59.4 gallons (225 L).
Current Free SO₂
Current free sulfur dioxide level in parts per million, measured by aeration-oxidation or Ripper method.
Target Free SO₂
Desired free SO2 level in ppm. Whites typically target 25-40 ppm; reds 20-35 ppm. Higher pH wines need more free SO2.
Wine pH
Current pH of the wine. Critical for determining molecular SO2 effectiveness. Most wines range from 3.0-3.8.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Wine Volume = 60, Current Free SO₂ = 15, Target Free SO₂ = 35, Wine pH = 3.4 = 4 input(s) provided
  2. Calculate Potassium Metabisulfite
    Potassium Metabisulfite
    7.89 = 7.89
  3. Calculate Antimicrobial Protection
    Yes (≥0.5 ppm molecular) = Yes (≥0.5 ppm molecular)
  4. Calculate KMS
    KMS
    1.38 = 1.38
  5. Calculate Campden Tablets
    Campden Tablets
    17.9 = 17.9

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