From the filter list choose Mechanical then at the Category choose Ducts then click on OK
Add fields to your schedule as shown
Put a name to the (Calculated Value) related to the item you want to add, I named it Duct length, then at the Formula I wrote as shown (Length/1000) asking Revit to call every single item of duct and divide it / 1000 then click on OK
And secondly we make a value for cost
I named it (average Cost Per Meter) and put the formula as shown, because the price for each linear foot, so it will be converted the length first to meter by diving the conversion factor from feet to meter them will multiply it to the cost, click on OK
Now our schedule is ready for showing
The two right columns are the two Calculated Values we’ve created, Revit MEP calculated length then cost
We have now the total ductwork length and estimating the average cost.