How much does half a gallon of water weigh?

To know how much half a gallon of water weigh, since 1 gallon of water weighs approximately 8.34 pounds, you can calculate the weight of half a gallon as follows:

1 gallon = 8.34 pounds
0.5 gallon = 8.34 pounds / 2
= 4.17 pounds

So therefore, half a gallon of water weighs approximately 4.17 pounds.