When the takeoff is linear with depth or height and width to get a volume quantity, a perimeter length as a drop-down would be helpful. To calculate the length of a rebar striup in a beam the perimeter is needed + [additional footage]. The same goes for any count that is converted to a volume.
Steven Hallman
EJ Smith Construction
Are you talking about calculating the length of a rebar stirrup? For example, say we have a 12"x24" footing/beam/column with #4 stirrups and 3" of coverage, you are looking for that 12"x24" cross section of your linear item, pulled in 3" for coverage, and then something added for the lap?
If so, you can do something like :

And something like this to get total ft of stirrups at certain spacing:

I love this community
nice job Kory!
I would be simpler, (([Width]+[Depth]*2)+1.25)*([Linear:FT]/[StirrupSpacingInches]/12)*[Adjustment]
I would have a Note: Adjustment: If Stirrups are doubled x 2
Round Count:
(([Diameter:IN]*3.1415)+24)/12)*(([Depth:FT]/[StirrupSpacingInches]/12)+[AdditionalTies]))