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Fysikere må av og til baske med Imperial / US enheter, så her kommer en rask oppklaring.
1 lbs = nøyaktig 453.592 37 gram
1 ft = 30.48 cm
1 fl oz = 28.41 ml = 0.96 US fl oz

og så braker det løs

1 gal = 4,55 l
1 US gal = 3,78 l
1 US dry gal = 4,40 l

og så et kort, oppklarende utdrag fra Wiki

The imperial gallon was based on the volume of 10 lb of distilled water weighed in air with brass weights with the barometer standing at 30 in Hg at a temperature of 62 °F. In 1963 this definition was refined as the space occupied by 10 lb of distilled water of density 0.998 859 g/ml weighed in air of density 0.001 217 g/ml against weights of density 8.136 g/ml. This works out to 4.545 964 591 L, or 277.420 cu in. The Weights and Measures Act of 1985 switched to a gallon of exactly 4.546 09 L (approximately 277.4 cu in) [3].

Legg merke til alle de logisk valgte tallene. Der SI baserer seg på potenser av 10, har Imperial mye morro: 1, 2, 3, 4, 8, 14, 112, 202 2/3, 220, 1760. Dette er jo enhver enhetskonverteringsoppgaves våte drøm. Til slutt noen få kloke ord om flytende føde. Enjoy.

Single servings of beverages are usually measured in fluid ounces. Milk is usually sold in cups or half pints (8 fluid ounces), pints, quarts and gallons. Water volume for sinks, bathtubs, ponds, swimming pools, etc., is usually described in gallons. The fluid ounce derives its name originally from being the volume of one ounce avoirdupois of water, but in the US it is defined as the 128th part of a US gallon, so a fluid ounce of water weighs about 1.043 ounces. The saying "a pint's a pound the world around" refers to 16 fluid ounces being one pint in the United States, but ironically it is only approximately true in the US. In the rest of the English-speaking world 20 fluid ounces make a pint, so it is said that "A pint of water weighs a pound and a quarter".