Enter the specific gravity of the fluid at 60 degrees Fahrenheit into the calculator to determine the API gravity.

API Gravity Formula

The following formula is used to calculate an API gravity. 

API G = (141.5/SG (@ 60) ) - 131.5
  • Where API G is the API gravity
  • SG is the specific gravity of the fluid at 60 degrees

To calculate the API gravity, divide 141.5 by the specific gravity at 60 degrees, then subtract 131.5.

What is API Gravity?

Definition:

API gravity is a scale used to measure the relative density of petroleum liquids with respect to temperature.

The scale was developed by the American Petroleum Institute so that most petroleum fluids would fall between 10 and 70 API gravity, which helps simplify analysis.

How to calculate API Gravity?

Example Problem:

The following example outlines the steps and information needed to calculate API gravity.

First, determine the specific gravity of the fluid at 60 degrees Fahrenheit.

For this example, the specific gravity is measured to be .65.

Next, the final step is to simply plug in the specific gravity into the formula above:

API G = (141.5/SG (@ 60) ) – 131.5

API G = (141.5/.65 ) – 131.5

API G = 86.192