Easy enough to do.
Measure one of the panels, length and width, multiply them, keeping the units the same. If it's a half in by eight inches, then you have four square inches in that one segment. Count the peaks on one side, each peak has two segments attached.
Determine the number of segments and multiply by the area of the one you measured. If you can't get a skinny enough ruler to get all the way down in the pleat, eyeball and estimate how much to add to the part that you can get the ruler on.
Be interesting to see that..

              I
            ,    D
         O.        O
      N.              N
   H,                    T
O.                           Have one either.

Thank you old slow & great one

With age comes wisdom

Wow who pissed in your Wheaties , I know how to figure surface area with proper measurements and most pleats are 1/2 deep paper or gauze types. Knowing that a simple measurement gets me in the same ball park. Oldnslow understood the question ! You'll never get my goat cause I simply don't give a sh*t !!!!