Crude Oil Grades: Sweet, Sour & Light

The Complete Guide to Crude Oil Grades: Sweet, Sour, Light, and Heavy

Jul 24, 2026

The Complete Guide to Crude Oil Grades: Sweet, Sour, Light, and Heavy

Introduction
Crude oil is often discussed as if it were a single commodity, but crude streams can differ dramatically in composition and value. Two of the most common descriptors are light versus heavy and sweet versus sour. These terms provide a quick indication of density and sulfur content, but refiners also examine acidity, metals, nitrogen, wax, salt, distillation behavior, and the yield of different fractions. Understanding crude oil grades helps explain why two barrels of crude can trade at different prices and why a refinery designed for one feedstock may not be able to process another efficiently.

Light and Heavy Crude
Light and heavy describe crude density, commonly expressed using API gravity. In general, higher API gravity indicates...

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