How do I count WIP positions on a moving conveyor?

Count the positions holding work in process at one moment, or read them from PLC tracking. Average a few counts across a shift so a stoppage does not skew the figure.

What unit cost belongs in the carrying value?

Material and conversion cost already spent on each unit. Selling price includes profit the buffer has not earned and would overstate the value finance is asked to accept.

Does higher availability always raise the value?

Not always in the same way. It cuts the parts lost to stops, but it also exposes more parts to quality and aging losses. Usable WIP is what remains after both are removed.

Why does kanban matter for conveyor WIP?

Kanban sets an upper limit on work in process, and the fixed positions on an accumulation conveyor enforce a limit of their own. Compare the carrying value with the limit you set.

Conveyors calculator

WIP on Conveyor Calculator

Value the work in process sitting on a conveyor and see how much of it stays usable after stops and quality losses. You need positions, turns, availability, yield and the unit cost carried.

What this calculator does

Usable work in process on a conveyor and the carrying value it holds, split into stop losses and quality losses.

Formula used

Gross conveyor WIP movement = conveyor WIP positions × turns per planning window
WIP unavailable due to stops = gross movement × (1 − availability % ÷ 100)
WIP lost to quality or aging = gross movement × availability % ÷ 100 × (1 − usable yield % ÷ 100)
Usable WIP on conveyor = gross movement × availability % ÷ 100 × usable yield % ÷ 100
WIP carrying value = usable WIP on conveyor × WIP unit cost

Inputs explained

Conveyor WIP Positions: Positions on the conveyor holding work in process.
WIP Turns per Planning Window: Times the buffer turns over per planning window.
Conveyor WIP Availability: Share of time the conveyor moves WIP without stops.
Usable WIP Yield: Share of buffered WIP that stays usable and sellable.
WIP Unit Cost: Material and conversion cost carried per WIP unit.

How to use the result

Best suited to justifying a smaller conveyor buffer, pricing excess WIP on the line, reviewing buffer turns with finance.
Carrying value covers inventory cost only; it leaves out floor space and handling cost. A window average; mix changes and ramp-up move the turns.

Current U.S. benchmarks

The U.S. has 21,668 machinery manufacturing establishments employing about 1,086,146 workers (Census County Business Patterns, 2023).

Common questions

How do I count WIP positions on a moving conveyor? Count the positions holding work in process at one moment, or read them from PLC tracking. Average a few counts across a shift so a stoppage does not skew the figure.
What unit cost belongs in the carrying value? Material and conversion cost already spent on each unit. Selling price includes profit the buffer has not earned and would overstate the value finance is asked to accept.
Does higher availability always raise the value? Not always in the same way. It cuts the parts lost to stops, but it also exposes more parts to quality and aging losses. Usable WIP is what remains after both are removed.
Why does kanban matter for conveyor WIP? Kanban sets an upper limit on work in process, and the fixed positions on an accumulation conveyor enforce a limit of their own. Compare the carrying value with the limit you set.

Last reviewed 2026-10-01.