Site maths
Packs, units & waste
- where
- target units
- net units
- waste (%)
- whole packs
- units per pack
Explain this equation
Turns a net quantity into whole supplier packs after adding a waste allowance. Use it for anything sold in fixed pack sizes.
N is the net number of units you need. w is the waste allowance as a percentage. T is the target quantity once waste is added. s is the number of units per pack, and n is the number of packs to buy. The calculator also reports units supplied and the surplus.
Multiplying by (1 + w/100) adds the waste percentage. The ceiling brackets ⌈ ⌉ mean round up to the next whole number, first to whole units and then to whole packs, because you cannot buy part of a pack.
1000 units plus 5% is 1050. With 500 per pack that is 3 packs, 1500 units, leaving 450 spare.
Watch out: waste is added before rounding to packs. Rounding up already gives some spare, so don't add a second allowance by mistake.
Convert a net quantity to whole supplier packs.
Enter your values to see the result.
Good to know
Rounding to packs happens after waste allowance. Pack size is supplier-specific.
Sources
- Geometry / arithmetic
This is a calculation aid, not a structural design or compliance certificate. Every default is an example, not a specification for your project.