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What Are Barrels Per Day? Definition & Origin

"Barrels per day" is a common unit used in tracking the production, storage, delivery, and usage of crude oil.
Photo of barrels containing crude oil with text overlay that reads "What Are Barrels Per Day?"

Crude oil’s origin of measurement in units of barrels goes back to the mid-19th century.

What Are Barrels Per Day?

Barrels per day is a unit of measurement used in tracking the production, storage, delivery, and usage of crude oil. Its abbreviations include bpd, bbl/d, and b/d.

A standard U.S. barrel of crude oil has a volume of 42 gallons, which is equivalent to 159 liters.

Storing crude oil in individual barrels is impractical due to the large volume of production, but tracking the flow of crude oil via the number of barrels has been the standard in the oil industry since the mid-19th century. 

When companies explore for crude oil and tap a deposit, the flow of oil extracted is measured in terms of barrels per day. Production of natural gas in liquid form is also measured in barrels per day.

What Is the Origin of Using Barrels?

When oil was discovered in Titusville, PA, in 1859, it was loaded into the only large containers available—whiskey barrels. Over the years, the industry standard became the 42-gallon barrel, which is still the standard paper measurement for pricing and pumping purposes, although oil rarely sees the inside of a barrel anymore. Interestingly, the first shortage in Titusville's 1859 oil boom was a shortage of barrels in which to store oil.

Nowadays, crude oil can be stored in steel barrels but only in very limited quantities. Sometimes, barrels are referred to as drums. However, a drum’s capacity is typically 55 gallons compared to a barrel's 42.

What Is a Barrel of Oil Equivalent (BOE)?

Barrel of oil equivalent (BOE) is a unit used in measuring an energy source. One BOE of a particular energy source can produce the equivalent amount of energy as the amount of crude oil contained in a single barrel. 

The energy content of a barrel of crude oil produced in the U.S. is 5.691 million British thermal units (BTUs). For natural gas, one cubic foot of energy equals 1,039 BTUs, so its barrels-of-oil equivalent is 5,477 cubic feet.

Barrel of oil equivalent is typically used for natural gas, but it can also be used for other energy sources such as coal and even uranium.

How Many Barrels Per Day Are Produced in the U.S?

According to the Energy Information Administration, total petroleum production in the U.S. was estimated to have averaged about 16.582 million barrels per day—with crude oil at 11.185 million bpd, and natural gas liquids at 5.397 million bpd.

How Many Barrels Per Day Are Consumed in the U.S?

In 2021, the U.S. was estimated to have consumed an average of about 19.78 million barrels of petroleum per day, according to the Energy Information Administration (EIA). Due to this high volume, the U.S. must import some of its crude oil and natural gas from other countries.