Conversion from US Dry pints to Cubic meters

Information about the US Dry pint (pt)

The United States dry pint is a unit of volume equal to 550.610471 millilitres, or 33.6 cubic inches. Its symbol is pt. It belongs to a separate American measuring system used for produce and grain rather than for liquids, and it is about sixteen per cent larger than the United States liquid pint of 473 millilitres.

Two parallel chains exist because two kinds of goods were once measured differently. Liquids descend from the wine gallon of 231 cubic inches, while dry goods descend from the Winchester bushel of 2150.42 cubic inches, a corn measure standardised in medieval England. Dividing the bushel by four gives a peck, by thirty-two a dry quart, and by sixty-four a dry pint, and none of those figures has any relation to the liquid chain.

Berries are where the unit is still met. Blueberries, raspberries and strawberries are sold in American markets in pint and quart baskets, and the basket is a dry measure. A pint of blueberries is therefore 551 millilitres of fruit, not 473, and a shopper comparing that basket with a pint of cream is comparing two different quantities under one name.

Nothing on a label resolves the ambiguity. Both are written pt, both are called a pint, and the word gives no clue as to which chain is meant. In practice the contents decide: if it pours, it is liquid measure, and if it is heaped, it is dry. That rule is reliable but it is nowhere written down, which is why converted American recipes so often disagree with one another.

Its existence is a survival from selling by bulk. Before cheap accurate scales, grain, apples, potatoes and shellfish were sold by filling a stamped measure and levelling it off, and the whole dry chain from bushel down to pint served that trade. Almost all of it has now been replaced by weight, and United States produce regulations increasingly specify pounds instead.

For conversion, the safest approach is to abandon the name entirely. A dry pint is 551 millilitres, a dry quart 1101, a peck 8.81 litres and a bushel 35.24. Writing the metric figure removes an ambiguity that the English word carries and cannot shed.

One United States dry pint equals 550.61 millilitres, 33.6 cubic inches, half a US dry quart, or about 1.164 US liquid pints.

Information about the Cubic meter (m³)

The cubic metre is the SI unit of volume, written m³. It is the volume of a cube one metre on each side, and because the metre is a base unit, every other volume unit in the system is derived from it. It holds a thousand litres, and a cubic metre of fresh water has a mass of very nearly one tonne, which is the single most useful fact about it.

Utilities are billed in it. Domestic water meters almost everywhere record consumption in cubic metres, and a household of four uses somewhere between 100 and 200 of them a year. Natural gas is metered the same way and then converted to energy for billing, because the heat released by a cubic metre of gas depends on its composition and has to be corrected for temperature and pressure at the meter.

Construction orders materials by it. Ready-mixed concrete is sold and delivered by the cubic metre, a standard truck carrying six to eight; excavation and earthworks are priced per cubic metre moved; and sawn timber, aggregate, topsoil and bark are all traded the same way. Because a cubic metre of concrete weighs about 2.4 tonnes, the unit also decides what a lorry or a crane can carry.

Freight uses it in a more subtle way. Shipping and removals quote volume in cubic metres, and air freight charges by whichever is greater, the actual mass or a volumetric mass calculated at a fixed ratio, commonly 167 kilograms to the cubic metre. Light bulky cargo is therefore priced by the space it occupies rather than by what it weighs, and the whole calculation runs on this unit.

Environmental measurement lives here too. River flow is given in cubic metres per second, reservoir capacity in millions of cubic metres, air quality as micrograms of pollutant per cubic metre of air, and ventilation as cubic metres per hour. A room four metres by five with a ceiling at two and a half holds fifty cubic metres of air, which is the sort of figure ventilation standards are written against.

Against imperial and United States units it converts to 35.315 cubic feet or 1.308 cubic yards. The cubic yard matters most in practice, because American concrete and excavation are ordered in it, and the two units are close enough that a mistaken figure looks plausible while being a third out.

One cubic metre equals 1000 litres, about 35.315 cubic feet, about 1.308 cubic yards, or about 264.2 US gallons.