API Gravity

API Gravity is a measure of crude-oil density developed by the American Petroleum Institute. It expresses how heavy or light a crude oil is relative to water, with higher values indicating lighter oils. API Gravity is calculated from specific gravity and is a critical quality parameter for determining crude value, refinery yields, and marketability. Lighter crudes (with higher API values) typically produce higher yields of valuable products such as gasoline, naphtha, and jet fuel. Heavier crudes (with lower API values) yield more residual fuel, bitumen, or heavier fractions and often require additional upgrading. Because refinery configurations vary, different refiners may assign different economic values to the same API grade depending on their equipment and crude-slate optimisation. In markets, API Gravity directly influences quality differentials, blending economics, crude-assay comparisons, and adjustment factors. Benchmark grades such as WTI and Brent are relatively light, while Canadian oil sands and Venezuelan crudes tend to be heavy. Traders analyse API Gravity alongside sulphur content, metals, total acid number, and distillation curves to evaluate relative value. Changes in regional API distribution—for example from increased shale-oil production—can shift refining margins, crack spreads, and downstream product balances.