Vegetable oil: why 198 g per cup is wrong
King Arthur publishes 198 g per US cup of vegetable oil. This site rejects that figure and publishes 218 g instead, from USDA FoodData Central (density 0.9214 g/mL, matching the composition of the substance). The reason:
198 g/cup implies a density of 0.8369 g/mL, below the physical density of every common food-grade vegetable oil. Soybean, canola, corn, sunflower and safflower oils all sit between 0.917 and 0.923 g/mL at room temperature — a well-established physical constant published by the FDA and Codex. King Arthur's figure appears to be an ounce-rounding artifact rather than a measurement of actual oil.
The arithmetic
| Source | 1 cup | Density | Status |
|---|---|---|---|
| King Arthur | 198 g | 0.8369 g/mL | Rejected on physics |
| USDA FoodData Central | 218 g | 0.9214 g/mL | Published here |
The independent standard
Where an independent physical standard exists for a substance, a source figure that falls outside it is rejected on the standard rather than on general physics. For vegetable oil, the applicable standard is Codex Alimentarius, which specifies both a composition and a density range for the substance. A cup weight implying a density outside that range cannot be a measurement of the standard-conforming substance; either the source measured something else, or the number is an arithmetic artifact carried over from a unit-conversion mistake. Full standards citation and reasoning is on the ingredient page.
The published figure and its sources
The full sourcing for vegetable oil, including every accepted and rejected figure, the state or filling method behind each, and the physics or standards reasoning applied, is on the ingredient page.
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