Cubic Foot (ft³)
A cubic foot (ft³) is a unit of volume in the imperial and US customary systems, defined as the amount of space enclosed by a cube with one-foot sides. It originated in English-speaking regions where it became a standard for measuring materials and space, especially in construction and trade. Today, the cubic foot remains common in American industries such as real estate, heating and cooling (HVAC), and the measurement of natural gas. It is equal to about 28.316 liters, allowing for practical use in both domestic and industrial settings. Even though most of the world uses metric units, the cubic foot maintains its significance in various technical and commercial fields.
Barrel (oil, bbl)
The oil barrel, symbol bbl, is a unit of volume commonly used in the petroleum industry. Its origins date back to the mid-19th century, when the American oil industry adopted the wooden barrel as a standard for storage and transportation. In 1866, the barrel was officially set at 42 US gallons (about 159 liters) to unify trade and pricing. Although physical barrels are no longer used, the “barrel” remains a widely recognized standard for oil production, consumption, and trading. The oil barrel is commonly referenced in discussions of energy, economics, and industrial development as a non-metric unit of volume.