Professional-grade petroleum engineering and oil market analytics tools.
The global energy industry relies on precise measurements and conversions. From trading desks in Houston and London to refinery control rooms, professionals need to convert between barrels, metric tonnes, gallons, and liters — and classify crude oil by density — every day. Our industry calculators bring these professional-grade tools to anyone who needs them.
Crude oil is not a single product — it varies enormously in density, sulfur content, and chemical composition. API Gravity is the primary classification metric, dividing crude into light, medium, heavy, and extra-heavy categories. Light sweet crude commands premium pricing because it produces the most valuable refined products with less processing. Our API Gravity calculator helps you convert between specific gravity and the API scale used universally in the petroleum industry.
API Gravity is the standard measure of how heavy or light crude oil is compared to water. Developed by the American Petroleum Institute, it uses an inverted scale where higher numbers mean lighter oil. Light crude (API > 31°) is more valuable because it yields more gasoline and diesel during refining. Heavy crude (API < 22°) requires complex processing but trades at a discount, creating arbitrage opportunities for specialized refineries.
Converting barrels to metric tonnes requires knowing the oil's density (API Gravity). The global average is approximately 7.33 barrels per tonne for 'typical' crude. However, light crudes like WTI yield 7.5-7.7 barrels per tonne, while heavy crudes like Mayan or Cold Lake yield only 6.5-7.0 barrels per tonne. Our Oil Unit Converter handles these density-dependent conversions automatically.
West Texas Intermediate (WTI) and Brent are the two main global oil price benchmarks. WTI (39.6° API) is a light, sweet crude priced at Cushing, Oklahoma. Brent (38.3° API) is a North Sea blend used as the global reference. Brent typically trades at a slight premium to WTI due to its relevance in international markets. The price spread between them reflects regional supply-demand dynamics.
Regional history drives the differences. North America adopted the 42-gallon barrel (bbl) in the 1860s Pennsylvania oil rush. Europe and Asia use metric tonnes for shipping and trade because vessel capacities are measured in deadweight tonnage. Refiners think in 'throughput per day' (barrels), while shipping companies think in weight (tonnes). This fragmentation makes unit conversion an essential daily task in the energy industry.
A crack spread is the difference between the price of crude oil and the prices of the refined products (gasoline, diesel, jet fuel) produced from it. It measures refining profitability. A '3-2-1' crack spread assumes 3 barrels of crude produce 2 barrels of gasoline and 1 barrel of distillate. Higher crack spreads mean more profitable refining. Understanding oil density (API Gravity) is crucial because it determines the product yield and thus the achievable crack spread.
Calculator methods and editorial structure reviewed July 11, 2026. Results are estimates; verify regulated rates, eligibility rules, and professional decisions with the cited primary source.