Enter the HHV value for the fuel (btu/ft^3) and the specific gravity of the fuel into the Wobbe Index Calculator. The calculator will evaluate the Wobbe Index. 

Wobbe Index Formula

The following two example problems outline the steps and information needed to calculate the Wobbe Index.

WI = Vc / (Gs)^1/2

Variables:

  • WI is the Wobbe Index ( )
  • Wv is the HHV value for the fuel (btu/ft^3) 
  • Gs is the specific gravity of the fuel 

How to Calculate Wobbe Index?

The following steps outline how to calculate the Wobbe Index.


  1. First, determine the HHV value for the fuel (btu/ft^3). 
  2. Next, determine the specific gravity of the fuel. 
  3. Next, gather the formula from above = WI = Vc / (Gs)^1/2.
  4. Finally, calculate the Wobbe Index.
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

HHV value for the fuel (btu/ft^3) = 1050

specific gravity of the fuel = .61

WI = Vc / (Gs)^1/2 = ?