When choosing the weight of the bat, many people ask what does -2 or -3 or even or +2 mean? The weight differential is the difference between the length and the weight. So a 34 inch bat with a -3 would weigh 34 - 3 = 31 ounces. A 33 inch bat with a +2 would weigh 33 + 2 = 35 ounces. Subtract or add the weight differential from the length and that will give you the weight in ounces.