Apologies- I thought I had posted this years ago.

Most measures are imprecise at best, many rely on body parts that change with every individual. The standard is a grown man of 'average' size. Typical are:

The Thumb (width) measured at the base of the nail. There are about 12 thumbs to a foot.
The hand, a measurement across the palm, excepting the thumb to the opposite side of the hand, most often used for horses, but not necessarily limited to that. About 4 thumbs.
The Span, the distance from thumb tip to little finger tip with the hand spread out as far as possible, roughly two hands or 8 thumbs.
The Foot, normally a mans foot, so women have to adjust, is about three hands long. Guilds requiring measuring often have a foot long stick.
The pace is a normal walking step.  A pace is a span or so smaller than a yard.
A yard is the distance from tip of nose to the end of the out stretched hands finger tips.There are three feet to the yard, which is a common moderate  distance measuring method. It is used for measuring cloth, lumber and similar moderate sized items where some exactness and uniformity is needed. Normally certain people are used for consistency's sake, and as this is a fairly regular measurement, many guilds have "official" Yard sticks.
A Rod is a measurement for land and other larger lengths. A Rod is 16.5 guild feet.
A Fathom is the distance from one out stretched finger tip to the other, with both arms out to the side at shoulder height. Often used for rope, and depth measurements made with rope. It is also defined as two Yards.
A Furlong is 40 Rods or about 1/20th of a league.
A league is defined as 5,000 paces (roughly 13,330 guild feet). Often the people doing the pacing are practiced hikers and the normal man will find the "league" to be several hundred paces longer than 5,000, as he counts his steps. Sometimes it is useful to know what your pace count per league is.

Weights are measured in pounds, ounces and various adjustments from these.
A pound is defined by the Guilds to be a certain weight. Small Stones are trimmed to this weight and sent to the various Cities as a standard from which other weights may be judged. It is becoming common to use metal weights for these, but the stones are still the official measurement.
A Stone is 14 pounds.
A Quarter is two stone.
A hundred Weight is four Quarters.
A Ton is 20 hundredweight
Smaller weights are the grain, the weight of one grain of wheat.
The pennyweight, or dram, is about 25 grains. It is the legal weight of a silver coin
The Ounce is 12 pennyweights/Drams and there are 12 ounces to the Megalian pound.

Volumetric measure is a bit more complex. The Pint is to weigh one pound. the variation in weights of various commodities made it normal to define the pint as that volume used to hold one pound of water. This now a standard set by the Mangai, and most guild halls that deal with volumetric measure will have a "standard" pint with which to maintain commonality.
2 Pints are a Quart
Four Quarts are a Gallon
5 Gallons is a cask (about 40 pounds)
10 gallons are a Pony Keg (about 80 pounds).
50 gallons are a hogshead (about 400 pounds).
5 hogsheads are a tun (about 2,000 pounds)
Note that the weight of the contents is what's important, so the weight of the keg is not considered. A Tun of beer or wine will weigh very close to 20 hundred weight (2240 pounds), making everything work out.

The standard period of time is the watch. There are 6 watches per day, nominally 3 day watches (morning, midday and afternoon) and three night watches (Evening, Midnight and the wee hours). Each watch is composed of 4 hours, although these are not easily measured, so terms like early in the watch, or about mid-watch are frequently used. Minutes are known, and defined as 60 counts (1 and 20, 2 and 20 etc. until 13 is reached, then just straight counting to 60). Counting more than a minute or two is most unusual, although the mathematicians have defined the hour as 60 minutes, but this is not widely known or cared about.

Money is confusing, as shaving coins is widespread. The Guilds attempt to enforce a weight standard with scales, but Kings tend to be irritated by commoners telling them their business, so it is a legal standard if the King chooses to pay you with his coins, regardless of how out of round they may be; although merchants are quick to quibble over a King's penny that seems a bit light or oblong.

1 League is close to 2.5 statute Miles or 2.2 NM  [5,000 yards]

COIN NAME  METAL    DIAM.   THICK.   MASS [lbs]   COINS/LB.   VALUE      WRITTEN
Farthing copper           * 0.05 0.02±           48           $0.25          f
Penny    copper          1"            0.05         0.08              12             $1               cp
mark         silver 0.9”       0.04         0.04               24           $10            Mk or M
half-crown   gold           0.5”       0.03       0.02                50           $50            h/Cr
crown      gold              0.7’”       0.04       0.04                25           $100           Cr
Ducat   Gold              1"           0.05       0.06                16           $181

*literally one quarter of a Copper coin

The "accepted" silver Mark is quite thin (about .04" or 1 mm) and perhaps 0.9 inch in diameter ( 2.2 cm). The farthings that used to be made by cutting pennies into quarters are both small and sharp, so an equivalent copper coin was made, as well as some other denominations. The farthing coin never caught on however.
The gold crown ,is nominally $100  although you may expect any merchant to weigh any gold coin carefully before making change. Gold coins are rare currency, and anyone displaying even a few will immediately cause a stir. It is equivalent to attempting to pass a very large bill in today's society.
Copper coins are valued at 1/10th the value ( by weight) of silver. This is useful for purchasing smaller amounts of goods. Buying copper ingots is normally 1/10th the value (by weight) of silver, so copper is not  well liked as an exchange for larger sums.
This message was last edited by the GM at 21:02, Tue 18 Jan 2022.