| Cubic feet (ft³) | Decaliters (daL) |
|---|---|
| 1 Cubic foot | 2.831684659 daL |
| 2 Cubic feet | 5.663369318 daL |
| 3 Cubic feet | 8.495053977 daL |
| 4 Cubic feet | 11.326738636 daL |
| 5 Cubic feet | 14.158423295 daL |
| 10 Cubic feet | 28.31684659 daL |
| 20 Cubic feet | 56.63369318 daL |
| 25 Cubic feet | 70.792116475 daL |
| 50 Cubic feet | 141.58423295 daL |
| 100 Cubic feet | 283.1684659 daL |
| Reference | Cubic feet (ft³) | Decaliters (daL) |
|---|---|---|
| A teaspoon | 0.000176573 ft³ | 0.0005 daL |
| A can of soft drink | 0.0116538 ft³ | 0.033 daL |
| A wine bottle | 0.026486 ft³ | 0.075 daL |
| A bathtub | 5.2972 ft³ | 15 daL |
| An Olympic swimming pool | 88286.7 ft³ | 250000 daL |
The cubic foot is a unit of volume equal to 1728 cubic inches, or 28.3168 litres. Its symbol is cu ft, sometimes written ft³. It is the volume of a cube one foot on each side, and it is the unit in which the United States measures natural gas, appliance capacity and air flow, three fields with almost nothing else in common.
Natural gas is its largest use by far. American gas meters record consumption in hundreds of cubic feet, bills are issued in thousands, and national reserves are quoted in trillions. Because the energy in a given volume of gas depends on its composition, utilities also publish a heating value per cubic foot, and the bill is the product of the two.
Appliances are sized in it. Refrigerator and freezer capacity in the United States is quoted in cubic feet, so a family refrigerator is about twenty and a chest freezer perhaps seven, and the same convention covers microwave ovens, washing machines and truck cargo boxes. Shoppers compare products by a number that describes usable space rather than external dimensions, which is genuinely more useful.
Air movement uses it per unit time. Fans, extractors, air conditioners and compressors are rated in cubic feet per minute, a figure abbreviated to CFM in every American catalogue. Ventilation standards are written as required air changes, which convert to cubic feet per minute once the room volume is known, so the unit sits on both sides of the calculation.
Materials and freight follow the same scale. Concrete, gravel, mulch and topsoil are sold by the cubic foot in smaller quantities and by the cubic yard in larger ones, twenty-seven cubic feet making one cubic yard. A cubic foot of fresh water weighs 62.4 pounds and holds about 7.48 United States gallons, which are the two figures most often needed alongside it.
Its metric equivalent is not memorable, at 28.3168 litres or 0.0283 cubic metres, and neither is its relationship to the cubic inch, at 1728. Those factors are why engineering outside the United States moved to metric volumes early even where lengths stayed imperial for longer.
One cubic foot equals 1728 cubic inches, about 28.317 litres, about 7.48 US gallons, or about 0.0283 cubic metres.
The decalitre is a unit of volume equal to ten litres. Its symbol is daL, and the spelling dekalitre is also accepted. It sits between the litre of the household and the hectolitre of the trade, and although it once had a settled place in European markets it is now among the least written of the metric volume units.
Its historical role was as a physical measure rather than a number. Nineteenth-century French markets sold grain, potatoes, chestnuts and dried beans out of stamped cylindrical vessels holding one decalitre, half a decalitre or a double one, and a trader's set of these was inspected and verified like a set of weights. Selling dry goods by volume was faster than weighing them and needed no balance, so the vessels did real work.
Weighing displaced it. Once cheap accurate scales became universal, dry goods moved to mass, which is fairer to the buyer because it does not depend on how densely a load happens to settle. The decalitre lost its purpose along with the practice, and the vessels survive in museums and in the vocabulary of a few older markets rather than in commerce.
The quantity itself remains perfectly ordinary. Ten litres is a large household bucket, half a jerrycan, the fuel tank of a scooter, or a fortnight of drinking water for one person. It is roughly the volume of a cubic vessel twenty-two centimetres on a side, and it weighs ten kilograms when filled with water.
What killed the unit as a written form was the same pressure that removed deca everywhere else. Metric practice steps by factors of a thousand, so litres serve until about a thousand of them and hectolitres take over for trade quantities. Ten litres is written 10 L, which is shorter than 1 daL, needs no explanation, and sorts correctly beside 5 L and 200 L in the same table.
When the unit does appear, usually in an old record or a translated document, the conversion is a single step. Multiply by ten for litres, divide by ten for hectolitres, and the resulting figure will match modern usage without any loss of precision.
One decalitre equals 10 litres, 0.1 hectolitres, about 2.64 US gallons, or about 2.2 imperial gallons.