Michelle allow me to talk myself out of a job. This is normally a conceptual problem with inventory values
It may or may not be a hassle to deal with day to day you decide.*
Lets boil down how inventory levels can be handled online.
Is it minus 1 to a products inventory only when an entire bolt is sold? No
Say there's 15 yards(15 inventory units) to a bolt, but since it's not sold in increments sold of 1 yard, how much inventory is there in 1 bolt?
In the example given the LCD is 1/4yd so every bolt is made of 15*(100/25) =60 inventory units.
That means a customer that buys 1/2 is buying 2 units of inventory (1/4yd)
Lets say 1ft square , how many inventory units does that make 1 physical bolt worth?
The LCD unit is generally based on the bare minimum that a business will ship
So this leaves making the theme reflect these increments(inventory units) when a customer adds inventory to thier cart.
And if selling bolts how those are handled as it puts multiple units into the cart at once, or there should be a seperate product for bolts since it's costs picking,packing & shipping factors are different.
*A side effect of this is you personally will begin to differently view how merchandise scales.