Enter the thickness (in) and the R-value into the Calculator. The calculator will evaluate the Insulation K Value. 

Insulation K Value Formula

K  = T / R


  • K is the Insulation K Value ((BTU-in/hr-ft^2-F))
  • T is the thickness (in)
  • R is the R-value

To calculate Insulation K Value, divide the thickness by the r-value of the material.

How to Calculate Insulation K Value?

The following steps outline how to calculate the Insulation K Value.

  1. First, determine the thickness (in). 
  2. Next, determine the R-value. 
  3. Next, gather the formula from above = K = T / R.
  4. Finally, calculate the Insulation K Value.
  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.

thickness (in) = 30

R-value = 2.5