Enter the peak systolic velocity and the end-diastolic velocity into the Calculator. The calculator will evaluate the Resistive Index. 

Resistive Index Formula

RI = (PSV - EDV) / PSV


  • RI is the Resistive Index ()
  • PSV is the peak systolic velocity
  • EDV is the end-diastolic velocity

To calculate Resistive Index, subtract the end-diastolic velocity from the peak systolic velocity, then divide by the peak systolic velocity.

How to Calculate Resistive Index?

The following steps outline how to calculate the Resistive Index.

  1. First, determine the peak systolic velocity. 
  2. Next, determine the end-diastolic velocity. 
  3. Next, gather the formula from above = RI = (PSV – EDV) / PSV.
  4. Finally, calculate the Resistive 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.

peak systolic velocity = 5

end-diastolic velocity = 14