Enter the nominal r-value and the percent decrease in performance (%) into the Calculator. The calculator will evaluate the Effective R-Value. 

Effective R-Value Formula

ER = NV * PD/100

Variables:

  • ER is the Effective R-Value ()
  • NV is the nominal r-value
  • PD is the percent decrease in performance (%)

To calculate the Effective R-Value, multiply the nominal r-value by the percent decrease in performance over 100.

How to Calculate Effective R-Value?

The following steps outline how to calculate the Effective R-Value.

  1. First, determine the nominal r-value. 
  2. Next, determine the percent decrease in performance (%). 
  3. Next, gather the formula from above = ER = NV * PD/100.
  4. Finally, calculate the Effective R-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.

nominal r-value = 2.25

percent decrease in performance (%) = 3