Table of contents |

2 Measures of length 3 Measures of volume 4 Measures of weight and mass |

A further difference between the systems in use in the two countries is that in cooking weights and measures, much more use is made of volume measures (cups and spoons) in the US, whereas in the UK quantities of dry ingredients are usually specified by weight; cup and spoon measurements are sometimes given, but these are not the same as the US standard cups and spoons, and in traditional recipes probably just reflect a favourite cup that the cook had to hand.

The full table of British measures of capacity (which are used alike for liquid and for dry commodities) is as follows:

- 4 gills = 1 pint
- 2 pints = 1 quart
- 4 quarts = 1 gallon
- 2 gallons = 1 peck
- 8 gallons (4 pecks) = 1 bushel
- 8 bushels = 1 quarter

- 20 minims = 1 fluid scruple
- 3 fluid scruples = 1 fluid drachm = 60 minims
- 8 fluid drachms = 1 fluid ounce
- 20 fluid ounces = 1 pint
- 8 pints = 1 gallon (160 fluid ounces)

As noted above, in the customary British system the units of dry measure are the same as those of liquid measure. In the United States these two are not the same, the gallon and its subdivisions are used in the measurement of liquids; the bushel, with its subdivisions, is used in the measurement of certain dry commodities. The U.S. gallon is divided into four liquid quarts and the U.S. bushel into 32 dry quarts. All the units of capacity or volume mentioned thus far are larger in the customary British system than in the U.S. system. But the British fluid ounce is smaller than the U.S. fluid ounce, because the British quart is divided into 40 fluid ounces whereas the U.S. quart is divided into 32 fluid ounces.

From this we see that in the customary British system an avoirdupois ounce of water at 62°F has a volume of one fluid ounce, because 10 pounds is equivalent to 160 avoirdupois ounces, and 1 gallon is equivalent to 4 quarts, or 160 fluid ounces. This convenient relation does not exist in the U.S. system because a U.S. gallon of water at 62°F weighs about 8 1/3 pounds, or 133 1/3 avoirdupois ounces, and the U.S. gallon is equivalent to 4 x 32, or 128 fluid ounces.

- 1 U.S. fluid ounce = 1.041 British fluid ounces
- 1 British fluid ounce = 0.961 U.S. fluid ounce
- 1 U.S. gallon = 0.833 British Imperial gallon
- 1 British Imperial gallon = 1.201 U.S. gallons

Among other differences between the customary British and the United States measurement systems, we should note that the use of the troy pound was abolished in Britain on January 6, 1879, with only the troy ounce and its subdivisions retained, whereas the troy pound (of 12 troy ounces) is still legal in the United States, although it is not now greatly used. Another important difference is the universal use in Britain, for body weight, of the stone of 14 pounds, this being a unit now unused in the United States, although its influence was shown in the practice until World War II of selling flour by the barrel of 196 pounds (14 stone).

In all the systems, the fundamental unit is the pound, and all other units are defined as fractions or multiples of it. The avoirdupois pound, the troy pound, and the apothecaries' pound are identical in Britain and the United States. The tables of British troy mass, and apothecaries' mass are the same as the corresponding United States tables, except for the British spelling "drachm" in the table of apothecaries' mass. The table of British avoirdupois mass is the same as the United States table up to 1 pound; above that point the table reads:

- 14 pounds = 1 stone
- 2 stones = 1 quarter = 28 pounds
- 4 quarters = 1 hundredweight = 112 pounds
- 20 hundredweight = 1 ton = 2240 pounds

Based on Appendices B and C of NIST Handbook 44. (Being a U.S. Government publication, it is presumably public domain).