The American Petroleum Institute gravity scale tells how heavy a petroleum liquid is compared with water. Higher API means lighter oil, which is generally more valuable because it yields more gasoline and diesel.
How to use the API Gravity Calculator
- Input
- Product
- Density at 60 °F
- Specific gravity at 60 °F
Results update as you type, every field has its own unit menu, and everything is calculated in your browser.
How it works
Choose a product or enter the density or specific gravity.
Inputs explained
| Field | What to enter |
|---|---|
| Input | Choose one: Product preset, Density, Specific gravity |
| Product | Choose one: Diesel No. 1-D, Diesel No. 2-D, Diesel No. 4-D, EN 590 diesel … |
| Density at 60 °F | Units: kg/m³, g/cm³, g/mL, lb/ft³, lb/in³ |
| Specific gravity at 60 °F | A number |
Example values
How the main result changes when Density at 60 °F changes and everything else stays at the example values above:
| Density at 60 °F (kg/m³) | API gravity (°API) |
|---|---|
| 425 | 37.961 |
| 637.5 | 37.961 |
| 850 | 37.961 |
| 1,062.5 | 37.961 |
| 1,275 | 37.961 |
| 1,700 | 37.961 |
Formula
°API = 141.5 / SG − 131.5 (SG at 60 °F relative to water)
Worked example
Inputs — Input: Product preset; Product: EN 590 diesel.
Results — Specific gravity = 0.835; API gravity = 37.961 °API; Classification = Light.
Key terms
- Specific gravity
- Density relative to water.
Frequently asked questions
What does API 10 mean?
The liquid has the same density as water.
Is high API oil better?
Light crude (high API) usually commands a higher price.
Why 60 °F?
It is the standard reference temperature in the US oil industry.
What is Brent's API gravity?
About 38°.