That depends on what substance, if any, is in the gallon.
If the gallon is empty, then the mass in it is zero grams.
1 gallon equals 1 gallon.
There are 3785.41 grams in one US gallon
There are four quarts in a gallon.
There are 3,785.41178 CCs in one gallon.
There are 16 cups in a gallon. Thus, one gallon of whole milk has 128 grams of fat.
1
4.8038
1 ounce = 28.34 grams 1 gram = 0.03 oz
Exactly there is 3785 milliliters in a gallon.
12
Four quarts equals one gallon.
3.78 liters