Crude Oil Blending Calculator

API gravity is a nonlinear transform of specific gravity (SG = 141.5 / (API + 131.5)), so averaging two API numbers directly gives a physically wrong answer. The calculator instead converts each crude to specific gravity, volume-weights the two SG values (the quantity that's actually additive when you mix liquids), and only converts the blended SG back to °API at the end — which is why the result won't match a naive average of the two input API values.

The calculator solves each target independently and separately: requiredPct1ForApi comes from the specific-gravity blending equation, while requiredPct1ForSulfur comes from a straight linear blend of sulfur weight percent. Unless your two crude streams happen to have API gravity and sulfur content that scale together in the same proportion, these two required percentages will land on different numbers — meeting one spec exactly generally won't simultaneously hit the other.

No — the calculator treats sulfur as a simple volume-weighted average, which it flags as a reasonable approximation for lighter crudes but not rigorous. Sulfur content is technically a weight-basis property, so for crudes with meaningfully different densities, a true weight-basis calculation would give a more accurate blend sulfur figure than this volume-basis shortcut.

It combines a $0.25/bbl premium for every API degree above a 30° baseline (rewarding lighter crude) with a $2/bbl penalty for every weight-percent of sulfur (penalizing sour crude), added together into a single per-barrel number. This is meant only as a directional signal of light/sweet-versus-heavy/sour blend economics — it isn't tied to actual posted crude prices or differentials in any specific market.