Question 1

How many gallons in an oil barrel?

Accepted Answer

A standard oil barrel is exactly 42 US gallons (159 liters). This size was standardized in Pennsylvania in 1866.

Question 2

Why are oil barrels 42 gallons?

Accepted Answer

Early Pennsylvania oil producers agreed on 42-gallon barrels (40 gallons + 2 for evaporation/spillage) to standardize trade.

Question 3

Are US and UK gallons the same?

Accepted Answer

No! US gallon = 3.785 liters. UK (Imperial) gallon = 4.546 liters. UK gallon is about 20% larger. Same applies to pints and fluid ounces.

Question 4

What's the most accurate way to measure volume?

Accepted Answer

For precision: measure by weight and convert using density. For liquids at eye level: read at the bottom of the meniscus curve.

Barrel Oil to Gallons Converter

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