Rock sugar and white sugar are both sucrose, but the purity of rock sugar is higher, so it can form large crystals. This is actually an arithmetic problem. The output ratio of sugar/alcohol is calculated as one liter of solution, and every 16.7 grams of sugar is converted into one degree of alcohol. Usually, a kilo of grapes becomes about one liter of wine mash after being pressed, and the wine yield of ordinary fresh grapes is usually less than 60%, and the wine liquid after complete fermentation is about 5 degrees. Then, it is estimated that the formula for making dry wine with the alcohol content of 12.5 degrees from 10 Jin of grapes is as follows:10 (12.5-5) *16.7 * 0.6 = 751. However, the sugar content of fresh grapes on the market may not reach, so it is usually appropriate to add more sugar and fatten yeast to produce more wine, and about two kilograms should be enough. When adding sugar, it is best not to add it directly, but to use a small amount of hot water to saccharify it into thick syrup and slowly merge it with the wine to speed up the eating of yeast.