If the density of water is 1.000 g/ml, what is the mass in grams of 1.000 gallons of water?

Recall that 1 gallon = 3.785 L, and 1 L = 1000 mL, so to calculate volume in millilitres, multiply by 3.785 and 1000, resulting in 3785 mL. Next, multiply volume by density to calculate mass (Density = Mass/Volume), so 3785 mL * 1.000 g / mL = 3785 g of water.