How Many Gallons Is 5 Liters. 5 it is part of the us customary system and chiefly used in the united states, but also in several other countries where it. Gallon is a unit of volume equal to 128 u.s. Fluid ounces, or about 3.785 liters. V(gal) = 5(l) × 0.26417 = 1.32085gal. Web 26 …