Weights and Measures
A resource for historical and fantasy fiction and RPGs

Length

Most traditional units of length are based on the human body.

However, a barleycorn, taken from the middle of an ear of barley, is the basis of formal English units of length (and weight!) from the Middle Ages on.

Notes on units

chain: A surveyor’s measure, not used until 1620 when it was introduced by the English mathematician Edmund Gunter (1581-1626). Gunter’s chain has the useful property that an acre is exactly 10 square chains.

cubit: (C14) From Latin cubitum elbow, cubit. The unit represents the length of a man’s forearm from his elbow to the tip of his outstretched middle finger. The Egyptian royal cubit or long cubit was equal to 28 digits or 7 palms (estimated at about 52.35 cm).

digit: (C15) From Latin digitus toe, finger.

ell: Old English eln the forearm; related to Old High German elina, Latin ulna, Greek ωλευη (ōlenē). According to Rowlett, the ell and the yard seem to be identified in some mediæval documents, with ulna being used for both. The etymology suggests a shorter unit, equivalent to the cubit. However, the English cloth ell is definitely longer than the yard; it seems to be the distance from the shoulder to the fingers of the opposite hand, reflecting the practice of cloth merchants of holding the cloth at the shoulder with one hand and pulling the piece through with the opposite hand.

fathom: From Old English fæthm, related to Old Frisian fethem, outstretched arms, Latin patēre, to gape. A fathom is the distance between a man’s outstretched fingertips. According to Rowlett, the fathom was a common unit in England in Saxon times, and it continued to be used for many purposes through the mediæval era. In fact, he notes, the length of the foot may have been defined, early in the twelfth century, specifically to assure that 1 foot = exactly ⅙ fathom.

foot (pl. feet): The natural foot (Latin pes naturalis), an ancient unit based directly on the length of human feet, was about 25 centimetres (about 10 in.) long. According to Rowlett, this unit was replaced in early Middle Eastern civilizations by a longer foot, roughly the length of the modern unit, that was an exact multiple of other natural units (as shown in the table above). This foot was used in both Greece and Rome; the Greek foot is estimated at 30.8 cm (12.1 in.) and the Roman foot (pes) at 29.6 cm (11.7 in.). Rowlett also notes that a manual foot (Latin pes manualis) of about 33.3 cm (13.1 in.), equal to two shaftments, was more common in northern Europe. He goes on to say that, in England, the Roman foot was replaced after the fall of Rome by the natural foot and the shaftment. The modern foot (of about 30.5 cm) did not appear until after the Norman Conquest of 1066 – and may have been an innovation of Henry I (1100-1135). Later in the 1100s, a “standard” foot was inscribed on the base of a column of St. Paul’s Church in London.

furlong: From Old English furlang, from furh furrow and lang long. The length of a furrow; traditionally, the distance a team of oxen could plow without needing a rest. According to Rowlett, long before the Norman Conquest in 1066, Saxon farmers in England were measuring distance in rods and furlongs and areas in acres.

hand: Based on the breadth of a man’s hand, it varied from 3–4 in. Traditionally used for measuring the height (from the front hoof to the whithers) of horses. (Also a longer measure, based on the length of the hand: 7–10 in.)

inch: Old English ynce, from the Latin uncia twelfth part (compare: ounce). The inch was widely defined as the width of a man’s thumb at the base of the nail. Uniquely in England, it was also defined as the length of three barleycorns laid end to end. According to Rowlett, in the history of English units the inch seems to come before the foot: after the Norman conquest of 1066 the foot was defined to equal 12 inches, rather than the inch being defined as one twelfth of a foot. (Now defined as exactly 0.0254 m.)

league: (C14) Middle English leuge, lege, from Latin leuga, leuca. Derived from an ancient Celtic unit and adopted by the Romans as the leuga, the league became a common unit of measurement throughout western Europe. It was intended to represent, roughly, the distance a person could walk in an hour. Rowlett notes that the Celtic unit seems to have been rather short (about 1½ Roman miles, which is roughly 1.4 statute miles), but the unit grew longer over time, ranging from about 2.4 to 4.6 miles. In England, however, leagues have always been used more often poetically than practically – and they are overused by contemporary fantasy authors wanting to give their works an “authentic” flavour!

mile: From Old English mīl, Latin mīlia (passum), a thousand (paces). Originally, the distance a Roman legion could march in 1000 paces, the measured distance between surviving milestones of Roman roads is close to 5000 feet. In mediæval Britain, several mile units were used, but eventually the mile was set at 8 furlongs, as the Romans had set their mile equal to 8 stadia (the stadium being about the same length as a furlong at 202.32 yd.). This was in use in the Middle Ages, but only defined by statute in 1592 (hence, statute mile). The nautical mile is defined to be the average distance on the Earth’s surface represented by one minute of latitude. For many years the British set the nautical mile at 6080 feet.

nail: From Old English nǣgl, related to Latin unguis fingernail, claw, Greek ονυξ (onux). Traditionally, it represented the length of the last two joints of the middle finger. Used for measuring cloth, and standardized as one twentieth of an ell.

(geometric) pace: (C13) Via Old French, from Latin passūs step. The distance between two successive falls of the same foot. (Although pace is also used to mean a single step.)

palm: (C14) paume, via Old French, from Latin palma palm. Also (confusingly) a synonym for span, especially in the U.S. According to Rowlett, in Roman times, the longer unit was known as the palmus major and the shorter one as the palmus minor.

rod: From Old English rodd rod, pole, related to Old Norse rudda club, of unknown origin. Also known as: pole, from Old English pāl, from Latin pālus, stake; perch from Old French perche, Latin pertica long staff; and lugg. The rod and the furlong were the basic distance units used by the Anglo-Saxon residents of England before the Norman conquest of 1066. According to Rowlett, rod, as a unit of length, is first attested 1450: The Saxons generally called this unit a gierd (see yard); the Normans a pole or a perch. The length of the rod was well established at least as early as the eighth century. It may have originated as the length of an ox-goad, a pole used to control a team of 8 oxen (4 yokes). It may have been considered equal to 20 natural feet or it may have been measured “by hand” as 30 shaftments. In any case, when the modern foot became established in the twelfth century, the royal government did not want to change the length of the rod, since that length was the basis of land measurement, land records, and taxes. Therefore the rod was redefined to equal 16½ of the new feet. This length was called the “king’s perch” at least as early as the time of King Richard the Lionheart (1198).

shaftment: From Old English sceaft shaft and mund hand. A shaftment is the width of the fist and outstretched thumb. A man could easily measure a shaft, rod or such like by hand, gripping it with both hands, thumbs extended and touching, and moving the grip hand over hand the whole length of the shaft. According to Rowlett, the shaftment of about 6½ in. was an important unit in Saxon England, but after the modern foot came into use in the twelfth century, the shaftment was reinterpreted as exactly ½ foot and continued in common use through at least the fifteenth century.

span: From Old English spann. The span of a man’s hand with fingers stretched out as far as possible. A quarter (of a yard) was the name of the unit of this length used for measuring cloth.

step: Old English stepe, stæpe. Also known as a military pace.

yard: From Old English gierd rod, twig, Old Saxon gerdia. Rowlett notes that the unit known as the gierd in Saxon times was actually the rod, not the yard. The yard was established after the Norman Conquest of 1066. The yard (as well as the foot) was set at close to its modern length during or around the time of Henry I (1100-1135); tradition has it that he decreed the yard should be the distance from the tip of his nose to the tip of his outstretched finger, thus defining the yard as exactly ½ fathom.

Area

Notes on units

acre: From Old English æcer, field, acre, related to Latin ager, Greek αγρος (agros), Sanskrit ajra. In use in England at least as early as the eighth century, the acre was traditionally the area that could be plowed in a day by a yoke of oxen. By the end of the ninth century it was generally understood to be the area of a field one furlong (40 rods or 660 ft.) long by 4 rods (66 ft.) wide.

rod: Yes, the same name was given to units of area and length! This was probably just a case of “square” being implicitly understood.

rood: Old English rōd. The area of a narrow strip of land one furlong (40 rods or 660 feet) long and one rod (16½ feet) wide.

Feudal settlements

This table follows a book I found in the library of Collingwood College, University of Durham. However, I neglected to note which… sorry.

commote: From Old Breton compot parcel of land. In each commote, six mænors are held by free notables, four by the king’s bondsmen, one each by the chancellor and the greater reeve. The two vills are for the use of the king; one held by the reeve, cultivated for the sustenence of the royal court – compare Welsh maerdref, the povost’s tref – and the other the king’s waste and summer pasture.

Weight

The fundamental unit of weight in all systems is the grain (gr., G.): The average weight of a dry barleycorn taken from the middle of an ear of barley.

Troy weight

The troy system is believed to be named for the French market town of Troyes, where English merchants traded at least as early as the time of Charlemagne (early ninth century). The troy pound was abolished in 1878 to avoid any commercial confusion with the avoirdupois pound.

Subdivision for gold and silver

Subdivision of the apothecaries

Tower weight

The tower system was used as the basis for English coinage during the mediæval era; it is named for the Tower of London, where the Royal Mint was located. In 1527, Henry VIII abolished the tower units in favor of the slightly larger troy units.

The progression of units is the same as in troy weight; the units themselves are 15/16 the weight of the equivalent troy units.

Avoirdupois weight

The avoirdupois system was introduced in England around 1300, replacing an older commercial system based on a merchants’ or mercantile pound (libra mercatoria) of 7200 grains divided into exactly 15 troy ounces. Scholars believe the avoirdupois pound was invented by wool merchants and modeled on a pound of 16 ounces used in Florence, Italy, which was an important buyer of English wool at the time.

Notes on units

clove: Varied from 6½ to 8 pounds. Used for wool.

dram or drachm: (C16) From Old French dragme, from Late Latin dragma, from Greek drakhme a handful.

hundredweight: From the mid 1300s, the hundredweight was defined in England as 112 pounds avoirdupois rather than 100 pounds that the name suggests.

last: Old English hlæst load. Generally the last is approximately 4000 pounds (or 80 bushels as a volume unit). (In the U.S., a last of wool was formerly 12 sacks or 4368 pounds.)

ounce: (C14) From Old French unce, from Latin uncia a twelfth part (the Roman pound was divided into 12 ounces).

pennyweight: The d in the traditional symbol dwt. is from the Latin word denarius for the small coin which was the Roman equivalent of a penny. Fineness of precious metals is often expressed as the number of gr. per dwt. that is precious metal; that is, the number of parts of the precious metal in 24 parts of the alloy.

pound: Old English pund, from Latin pondō pound, pondus weight.

sack: Old English sacc, from Latin saccus bag. In Britain, the sack was a traditional measure for wool, fixed by Edward III at 364 pounds (26 stone) in 1340. Sacks of other commodities are of different sizes and weights.

scruple: From Latin scrūpulus a small weight, from scrūpus rough stone.

stone: Old English stān. According to Rowlett, the stone originally varied in size, both from place to place and according to the nature of the item being weighed: A stone of sugar was traditionally 8 pounds, while a stone of wool could be as much as 24 pounds. Eventually the stone was set at 14 pounds avoirdupois, equal to ½ quarter or ⅛ hundredweight.

tod: (C15) Probably related to Old Frisian todde rag, Old High German zotta tuft of hair. The tod was used for wool.

ton: See: tun.

wey: From Old English wœge weight. Originally the wey was about two hundredweight. Used for wool.

Capacity

Liquid and dry measure

This table is adapted directly from Jefferson (1790). However, I suspect Jefferson may have regularised the contemporary state of affairs…

Beer and ale from sizes.com . “The surviving subdivisions indicate that the original tun must have been 256 gallons, but by 1347 it had been 252 gallons for so long that the King's commissioners could not explain the loss of the 4 gallons. By at least 1454 the barrel of ale contained 32 gallons (one-eighth of the original, 256-gallon tun), and the barrel of beer contained 36 gallons. An act of 1531 (23 Henry VIII chap. 4) confirmed these figures. By Elizabeth I's time, the gallons referred to were ale gallons of 282 cubic inches.”

Wine from sizes.com . “From at least the 14th century the barrel of wine has contained 31.5 gallons, one-eighth of the tun of 252 gallons. The gallons are wine gallons of 231 cubic inches, used by the Excise for centuries before being legalized by an act of 1707 (Anne chap. 27 s 17).”

Apothecaries’ liquid measure

Notes on units

barrel: (C14) From Old French baril.

bushel: (C14) From Old French boissel, from boisse one sixth of a bushel, of Gaulish origin.

butt: (C14) From Old French botte, from Old Provençale bota, Late Latin buttis cask.

coomb: Of obscure origin.

drachm: See dram.

firkin: (C14) From Middle Dutch vierde fourth + -kijn small.

gallon: (C13) From Old Northern French galon (Old French jalon), perhaps of Celtic origin, although Rowlett suggests Latin galeta pailful. Gallons of various sizes have been used in Europe ever since Roman times. 231 cubic inches; The old English wine gallon of 231 cu. in., perhaps the volume of 8 troy pounds of wine, originated in mediæval times but was not standardized until 1707, during the reign of Queen Anne. The earliest official definition of a dry gallon in Britain is a 1303 proclamation of Edward I, where the gallon is defined as the volume of 8 pounds of wheat. Dry (grain) gallons have tended to be larger than liquid gallons as they’re heaped rather than “struck” (leveled) containers.

gill: (C14) From Old French gille vat, tub, from Late Latin gillo a cooling vessel for liquids.

hogshead: (C14) Of obscure origin.

kilderkin: (C14) From Middle Dutch kinderkijn, from kintal hundredweight, from Middle Latin quintale.

load: n Britain prior to modern times, a load was sometimes a standardized unit, but it varied with the commodity being carried. A typical size was 40 bushels (roughly 1.4 cubic meters).

minim: (C15, in its musical sense: a half-note) from Latin minimus smallest. In pharmacy, the term drop traditionally meant the same thing as 1 minim. The traditional abbreviation – gt. for a single drop, gtt. for many – is from Latin gutta drop.

peck: (C13) From Anglo-Norman pek, of obscure origin.

pint: (C14) From Old French pinte, of unknown origin. Rowlett suggets it may come from the Latin pincta, painted, referring to a marking at the one-pint level on a larger container.

pipe: (C14) From Old French. The British pipe was usually used as a wine measure, but even different types of wine had different size pipes.

pottle: (C14) From Old French potel, a small pot.

puncheon: (C15) poncion, from Old French ponchon, of unknown origin.

quart: (C14) From Old French quarte, from Latin quartus fourth.

quarter: (C13) From Old French quartier, from Latin quartārius, a fourth part. A quarter of a tun. According to Rowlett, this unit was also known as a seam, Old English for the load of a pack animal. A seam or quarter was equal to 8 bushels at least by the end of the thirteenth century.

rundlet: Dates back to the Middle Ages.

strike: Compare strickle (Old English stricel), a board used for sweeping off excess maerial in a container, also known as a strike.

tertian: (C14?) From Latin tertius third. A third of a tun.

tierce: (C15) From Old French, feminine of tiers, from Latin tertius third.

tun or ton: From Old English tunne, related to Old High German, Old Norse tunna, Medieval Latin tunna.

References

Thomas Jefferson: Plan for establishing uniformity in the Coinage, Weights, and Measures of the United States

Russ Rowlett: How Many? A Dictionary of Units of Measurement

sizes.com: Sizes, grades, units, scales, calendars, chronologies; all things quantifiable quantified