Net material represents what actually forms the finished unit. Gross material also includes bars, cuts, offcuts and waste required for purchasing and fabrication. These figures answer different questions.
When net calculations help
Net calculations clarify technical composition and help compare opening configurations. They show theoretical consumption for the selected dimensions and components.
When gross material is essential
Purchasing and planning must consider bar stock, cuts and process losses. Ignoring that difference makes quoted costs look lower than actual costs.
Define the rule before pricing
Record the calculation basis, waste allowance and stage at which each value is applied. Apply consistent criteria to comparable proposals and revise them when the process changes.
Avoid mixing the concepts
Show technical calculations and purchasing costs separately when that helps the team check them. A dimension change should not be hidden inside one total.