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United States gallon

Convert the U.S. gallon to other major units of capacity

Print a chart for converting between U.S. gallons and liters

In the United States, the only legal gallon is a unit of liquid capacity = 231 cubic inches = 3,785.411 784 cubic centimeters. This is not the only gallon that has been used in the United States; for example, in the late 19ᵗʰ century some states had a 282-cubic-inch “milk gallon.” And see U.S. dry gallon. Symbol, gal.

The state of New York had a liquid gallon defined in law as the volume occupied by 8 pounds avoirdupois of water at 39.83 degrees Fahrenheit at a barometric pressure at 30 inches. That would make it about 221.184 cubic inches. It was abolished by an act of 11 April 1852.

The United States gallon descends from the English wine gallon.

The “gallon size” can of paint

The gallon can of paint does not necessarily contain 128 U.S. fluid ounces of paint:

Actual fluid ounces in cans/pails commonly called gallon, three gallon or five gallon will be from 114-128, 342-384, or 570-640, respectively, based on customers' choice of paint/stain and color.

Lowe's flyer, July 2014.

Lowe's is careful to refer to the cans as “gallon size cans” not “gallon cans”. Here one must sympathize with the seller. Economies of scale dictate a standardized 128-fluid ounce can, but room must be left in the can for adding colorants, and the amount of colorant varies with the color. It is like a barista not filling a paper cup of coffee-to-go to the brim, to leave room for cream.

sources

The gallon is a vessel containing 58372.2 grains (8.3389 pounds avoirdupois) of the standard pound of distilled water, at the temperature of maximum density of water, the vessel being weighed in air in which the barometer is 30 inches at 62° Fahrenheit. ... These standards were adopted by the Treasury Department on the recommendation of Mr. Hassler, in 1832.

U. S. Senate, 34th Congress, 3rd Session.
Ex. Doc. No. 27.
Report of the Secretary of the Treasury on the Construction and Distribution of Weights and Measures.
Washington: A. O. P. Nicholson, printer, 1857.
Page 5.