We add potassium metabisulfite, a compound that contains approximately 57 percent sulfur dioxide (SO2), at the crusher, after secondary fermentation is complete, then every six months until the wine is ready for bottling, and finally at bottling. This releases sulfur dioxide gas into the must or wine and helps inhibit spoilage. To determine the amount needed to achieve the desired parts per million (ppm) concentration, use this formula:

Grams of potassium metabisulfite to add = desired ppm SO2 x gallons of wine/must x 0.00757

The following information provides a simple way for you to calculate your additions:

To add 30 ppm:
Grams of potassium metabisulfite to add = gallons of must x 0.23

To add 40 ppm:
Grams of potassium metabisulfite to add = gallons of must x 0.30

To add 50 ppm:
Grams of potassium metabisulfite to add = gallons of must x 0.38

Quick Reference Measurements Guide
One level teaspoon of potassium metabisulfite = 6.3 grams

How much potassium metabisulfite should I use?

When we add potassium metabisulfite to wine, we strive to achieve 0.5 ppm molecular in red wine and 0.8 ppm molecular in white wine. Use the following table as a guide:

How do I add potassium metabisulfite to my wine?

An easy way to add potassium metabisulfite additions to wine is to use a stock solution. You can prepare a stock solution by dissolving 18.11 grams of potassium metabisulfite in 100ml of distilled water. Then, add the stock solution to the wine in the amount shown in the following table: