Definition
Wastage percentage is the share of material you buy that does not end up in the finished product. It includes cut offcuts, grade rejects, layout-driven loss (especially around figured timbers and stone), and breakage. It is applied to net material requirement to derive order quantity.
Example
Worked exampleA joinery shop needs 47.5 lin.m of finished oak. With an 18% wastage factor, they order 47.5 × 1.18 = 56.05 lin.m. The 8.55 lin.m gap is real material consumed but never billed to the client.
Why it matters
Most shops apply a blanket 10% wastage. The reality varies dramatically by material — figured timber runs at 22%, granite slabs at 25%+, MDF at 5%. Using one number across all materials is the single biggest pricing leak in custom fabrication.