Why not just add the scrap percentage to the order quantity?

Because scrap is a share of units started, not of good units. At 10% scrap, 1,000 good units need 1,112 starts (1,000 ÷ 0.9, rounded up), not 1,100. The gap widens as scrap rises.

Should reworked units count as scrap?

No, unless they are finally discarded. Rework that passes still ships, so it does not raise starts, but it uses line or rework time. OEE quality still counts it as a loss because it failed the first time.

Does a reject caught mid-line cost as much line time?

No. A reject pulled halfway used only the upstream stations, so it costs less line time than a finished reject. The starts figure still holds; the line time figure overstates the loss for mid-line rejects.

How does scrap show up in OEE?

As the quality factor, good count ÷ total count. A 1.97% scrap rate caps quality at 98.03%, lower if you count rework. The run time spent making the rejects is the line time this calculator reports.

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Scrap Impact on Line Output Calculator

Turn a run's scrap count into the extra starts and line time an order needs, and check the rate against your limit. You need reject counts, the order quantity and line rate.

What this calculator does

How scrap cuts good line output, and how many extra units you must start to ship an order.

Formula used

Scrap rate s = scrapped units ÷ total units produced; margin to limit = limit − s × 100
Units to start = CEILING(good units needed ÷ (1 − s))
Extra starts = units to start − good units needed
Line time on scrap (min) = extra starts ÷ running line rate × 60
Good output rate = line rate × (1 − s); good output lost per hour = line rate × s

Inputs explained

Scrapped Units: Unrecoverable rejects from the reject counter or scrap log.
Total Units Produced: Good plus scrapped units over the same run.
Good Units Needed: Order quantity or demand the line must ship.
Running Line Rate: Gross units per hour while running, rejects included.
Scrap Rate Limit: Scrap allowance from your quote or control plan.

How to use the result

Best suited to setting the start quantity for an order, checking a run against the quoted scrap allowance.
Reworked units that pass are not scrap here; the line time rework takes is not counted. Prices no material, labor or disposal; it counts units and line time only.

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

Why not just add the scrap percentage to the order quantity? Because scrap is a share of units started, not of good units. At 10% scrap, 1,000 good units need 1,112 starts (1,000 ÷ 0.9, rounded up), not 1,100. The gap widens as scrap rises.
Should reworked units count as scrap? No, unless they are finally discarded. Rework that passes still ships, so it does not raise starts, but it uses line or rework time. OEE quality still counts it as a loss because it failed the first time.
Does a reject caught mid-line cost as much line time? No. A reject pulled halfway used only the upstream stations, so it costs less line time than a finished reject. The starts figure still holds; the line time figure overstates the loss for mid-line rejects.
How does scrap show up in OEE? As the quality factor, good count ÷ total count. A 1.97% scrap rate caps quality at 98.03%, lower if you count rework. The run time spent making the rejects is the line time this calculator reports.

Last reviewed 2026-10-01.