Dry measures areunits ofvolume to measurebulk commodities that are notfluids and that were typically shipped and sold in standardized containers such asbarrels. They have largely been replaced by the units used for measuring volumes in themetric system and liquid volumes in theimperial system but are still used for some commodities in theUS customary system. They were or are typically used inagriculture,agronomy, andcommodity markets to measuregrain, driedbeans, dried and fresh produce, and someseafood. They were formerly used for many other foods, such assalt pork andsalted fish, and for industrial commodities such ascoal,cement, andlime.
The names are often the same as for the units used to measure liquids, despite representing different volumes. The larger volumes of the dry measures apparently arose because they were based on heaped rather than "struck" (leveled) containers.[1]
Today, many units nominally of dry measure have become standardized as units ofmass (seebushel); and many other units are commonly conflated or confused with units of mass.
In the originalmetric system, the unit of dry volume was thestere, equal to a one-meter cube, but this is not part of themodern metric system; theliter and thecubic meter are now used. However, the stere is still widely used forfirewood.
InUS customary units, three units of volume exist both in a dry and a liquid version, with the same name but different values—the drybarrel, the dryquart, and the drypint—while thebushel andpeck are only used for dry goods.
Imperial units of volume are the same for both dry and liquid goods, and have a different value from both the dry and liquid US versions of the pint and quart: an imperial pint and quart are 20.095% larger than their US liquid counterparts and 3.21% larger than their US dry counterparts, whereas the imperial peck and imperial bushel were deleted from the relevant UK statute in 1968.
Many of the units are associated with particular goods, and there are also special measures for specific goods, such as thecord of wood, the sack, thebale of wool or cotton, the box of fruit,etc.
Because it is difficult to measure actual volume and easy to measure mass, many of these units are now also defined as units of mass, specific to each commodity, so a bushel of apples is a different weight from a bushel of wheat (weighed at a specific moisture level). Indeed, the bushel, the best-known unit of dry measure as the quoted unit incommodity markets, is a unit of mass in those contexts.
Conversely, theton used in specifyingtonnage and in freight calculations is often a volume measurement rather than a mass measurement.
In UScooking, dry and liquid measures are the same: thecup, thetablespoon, theteaspoon.
In the US, the dry quart and dry pint are exactly15121/92400 larger than their liquid counterparts, while the dry barrel is exactly1/33 smaller than the fluid barrel, except for barrels of beer (dry barrels are exactly5/341 smaller) and barrels of oil (dry barrels are exactly3/11 smaller).
The volume of bulk goods is usually measured by filling a standard container, so the containers' names and the units' names are often the same, and indeed both are called "measures". Normally, a level or struck measure is assumed, with the excess being swept off level ("struck") with the measure's brim—the stick used for this is called a "strickle". Sometimes heaped or heaping measures are used, with the commodity heaped in a cone above the measure.
There was historically[clarification needed] a tendency for landowners to demand heaped bushels of commodities from their peasants, while at the same time peasants were obliged to purchase commodities from stricken containers. Rules outlawing this practice were circumvented through use of heavy round strickles, which would compress the contents of a bushel.[2]
| unit | symbol | inches3 [3] | volume[4] | Imperial equivalent |
|---|---|---|---|---|
| 1pint | pt | 33.6003125 | 550.6104713575 ml | 0.9689390 pints |
| 1quart | qt | 67.200625 | 1.101220942715 L | 1.9378779 pints |
| 1peck | pk | 537.605 | 8.80976754172 L | 1.9378779 gallons |
| 1bushel | bu | 2,150.42[5] | 35.23907016688 L | 7.7515118 gallons |
| 1barrel | bbl | 7,056 | 115.627123584 L | 25.4344115 gallons |