# API Gravity Calculator

URL: https://speedycalculator.com/calculators/physics/api-gravity/
Last updated: 2026-10-30

> The API gravity calculator converts the density or specific gravity of a petroleum liquid at 60 °F into its API gravity, and classifies crude oil as light, medium, heavy or extra heavy.

## Inputs

- Input
- Product
- Density at 60 °F (kg/m³, g/cm³, g/mL, lb/ft³, lb/in³)
- Specific gravity at 60 °F

## Results

- Specific gravity
- API gravity
- Classification

## Formula

```
°API = 141.5 / SG − 131.5  (SG at 60 °F relative to water)
```

## Explanation

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

FieldWhat to enterInputChoose one: Product preset, Density, Specific gravityProductChoose one: Diesel No. 1-D, Diesel No. 2-D, Diesel No. 4-D, EN 590 diesel …Density at 60 °FUnits: kg/m³, g/cm³, g/mL, lb/ft³, lb/in³Specific gravity at 60 °FA 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)42537.961637.537.96185037.9611,062.537.9611,27537.9611,70037.961

## 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.

## FAQ

**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°.


## Sources

- [The Engineering ToolBox](https://www.engineeringtoolbox.com/)
- [U.S. EIA – Crude oil API gravity](https://www.eia.gov/)