formula help for estimating

[browndog1229]

First time listener first time caller. To say i am a rookie at excel would be a understatement. I use 4'x12' sheet metal for fabricating square duct work. All duct work is 4' long but the widths change. so for example I would have 150' of 16"x 20". how many 4'x12' sheets would i need.

A1= length
B1= width
C1=height
D1=how many sheets

 

[Dryver14]

This is a very difficult formula as you will be wanting the minimum of wastage and so will want to change cutting direction to minimize it.