In case anyone saw Tasty Trade's discussion on IV Percentile vs IV Rank with Jacob , you may want to get your hands on the Think or Swim (TOS) IV Percentile script. I have included the thinkScript code I developed below. If you do not know how to add a script to TOS, there are tons of resources online. Just Google "add study to TOS" and you'll find a plethora of examples and guides. ~\Desktop\LCM_PercentileSTUDY.ts.html declare lower ; # Mark Laczynski # 3.13.2014 # look at 1 year of history input length = 252 ; #clean up the IV data from TOS rec clean_iv_r = if ( isNaN (imp_volatility()) and ! isNaN ( close )) then clean_iv_r[ 1 ] else imp_volatility(); rec iv_today_r = GetValue (clean_iv_r, -length); rec bar_number_of_todays_iv_projected_back = if IsNaN (bar_number_of_todays_iv_projected_back[ 1 ]) then 0 else if ( isNaN (iv_today_r)) then BarNumber () else bar_number_of_todays_iv_projected_back [ 1 ]; rec iv_today_p