I would post this on Quora, since it is more of a "just wondering" sort of question, except that I much prefer StackExchange's platform:

  • As weird as Imperial units generally are, English volume units surprisingly make a lot of sense. I'm thinking there must be a reason for this... is there?


  • 1 cup = 8 fluid ounces
  • 1 pint = 2 cups (16 fluid ounces)
  • 1 quart = 2 pints (32 fluid ounces)
  • 1 gallon = 4 quarts (128 fluid ounces)

Compared to some other craziness in the world of non-SI units, these make a ton of sense:

  • They are all base-2 multiples, which is really easy for converting one unit to another, and for easily covering the "space of interest" (i.e., you'll never need to say 0.031 gallons, since you can instead say 4 fl. oz).
  • Even the names are suggestive / helpful:
    • a quart is a quarter of a gallon.

Was there a royal scientists or some-such academic responsible for this lack of insanity?

  • 2
    $\begingroup$ Furthermore, has there been a common term for 64 ounces that disappeared or was it skipped; in any case, why? $\endgroup$ – Ben Oct 14 '16 at 21:26
  • 2
    $\begingroup$ @ben: 2 quarts is one pottle; 2 pottles is one gallon, according to one list of English volume units. I've heard elsewhere more volume units based on the binary system: 2 mouthfuls is one jigger, 2 jiggers is one jack, 2 jacks is one jill (or gill), 2 jills is one cup, etc. $\endgroup$ – David Cary Oct 25 '16 at 0:41

The introduction of these units precedes the Royal Society by a long time, and the story of their origins is murky. Pints, pecks, gallons and quarts appeared in the so-called "Winchester Standards" instituted in England by Henry VII in 1495. A standard bushel, gallon and quart made of bronze, issued in 1497 and stamped with the mark of Henry VII are still preserved in the British Museum. Later they became the basis of the Imperial Units defined in the British Weights and Measures Act of 1824. One of the earliest documents defining the gallon, bushel and quarter, is the Tractatus de Ponderibus et Mensuris, officially listed as an "ancient statute of uncertain date", but estimated as c. 1250 - 1305 and sometimes attributed to Henry III or Edward I:

"By Consent of the whole Realm the King’s Measure was made, so that... Twenty-pence make an Ounce; and Twelve Ounces make a Pound, and Eight Pounds make a Gallon of Wine; and Eight Gallons of Wine make a Bushel of London; which is the Eighth Part of a Quarter."

But even in the Imperial Units the pint was still 20 fluid ounces, so it was not fully binarized even in 1824. There was no unit for 4 pints, I guess half-gallon worked well enough, but 1/4 pint was called gill.

The reason the "Winchester Standards" are so called is that c. 970, when the capital of England was Winchester, the then king Edgar the Peaceful allegedly instituted the said units already. Alas, no traces of them are found before the Norman Conquest of 1066, a century later, and most unit names (quarter, bushel, peck, gallon, pottle, quart, pint) have French roots. The units in use prior to the Norman Conquest, and even as late as 1196, were different and had Latin derived names (sester, amber, mitta, coomb, seam), although seams and sesters can be roughly equated to quarters and pints.

As a side curiosity, the ancient Chinese units of weight went in multiples of 16, and we also do not know if some sage was behind it, see What is the most ancient civilization that used base-16 (hexadecimal) number system?

  • $\begingroup$ Thanks so much! Just to clarify, the handy base-2 multiples happened some time "fairly recently"? That is to say, some time after 1824? I find the history of science and math fascinating, but am totally ignorant. $\endgroup$ – Mike Williamson Oct 17 '16 at 18:21
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    $\begingroup$ @MikeWilliamson Only the most cleaned up version. The tradition of eights and quarters is already apparent in "Winchester Standards", as the Tractatus indicates, although it is not complete there. $\endgroup$ – Conifold Oct 17 '16 at 18:42

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