Density of Oil: 700–950 kg/m³ — Cooking Oils, Motor Oil, Crude Oil, and API Gravity

All oils are less dense than water (1,000 kg/m³) and will float on water.

Oil density decreases with increasing temperature at approximately 0.6–0.7 kg/m³ per °C. Values above are at standard reference temperature (15°C or 20°C as noted).

The data below gives reference densities at standard temperature (15°C or 20°C). Within the same oil type, actual density can vary by about ±20 kg/m³ depending on variety, origin, and refining level.

Extra heavy crude and bitumen (density > 1,000 kg/m³) are the only oil types that can sink in fresh water. This is relevant for environmental spill response: most crude oil spills float, but bitumen-derived diluted bitumen ("dilbit") can sink after the lighter diluent evaporates.

For broader liquid and material comparisons, open the density table.

API Gravity is the petroleum industry's standard measure of how heavy or light crude oil is relative to water. It was developed by the American Petroleum Institute (API) and is used universally in oil trading, refining, and pipeline specifications. Unlike density, API Gravity increases as oil gets lighter, making it an inverse density scale.

The relationship between API Gravity and specific gravity (density relative to water at 60°F / 15.6°C) follows the same mass-per-volume idea explained in what is density. For the broader equation workflow, see the density formula guide.

Light crude commands a price premium because it yields more high-value products (gasoline, jet fuel, diesel) per barrel with less refining energy.

All common oils have densities between 700 and 970 kg/m³, compared to fresh water at 1,000 kg/m³ and sea water at approximately 1,025 kg/m³. Because oil is less dense than water, it floats — the less dense fluid always rises above the denser fluid when the two are in contact and not miscible. See density of water for the full reference.

Oil and water do not mix because water molecules are polar (they have positive and negative ends that attract each other) while oil molecules are non-polar. This polarity difference — not density — is the primary reason oil and water separate. Density determines which layer sits on top once they have separated.

The density difference between oil and water has major practical consequences. In oil spill response, floating oil can be contained with booms and skimmed from the surface — but bitumen-derived oils that sink require different recovery methods. In cooking, oil floats on water-based sauces and marinades. In engine lubrication, oil sits above water contamination in a sump. In petroleum refining, density measurement is one of the primary quality control parameters. For the salinity reference, see density of sea water.

Like all liquids, oil density decreases as temperature increases. The thermal expansion coefficient of most oils is approximately 0.6–0.7 kg/m³ per °C, meaning oil becomes about 0.07% less dense for every 1°C rise in temperature. This is significantly higher than water's thermal expansion near room temperature.

Temperature correction matters in several practical contexts: petroleum custody transfer (oil is bought and sold by volume at a reference temperature of 15°C), engine oil performance (cold oil is denser and more viscous, affecting cold-start lubrication), and cooking (hot oil is less dense, which affects how food sinks or floats during frying).