Scrap Rate and Yield Calculator
Scrap rate, first-pass yield, and the rolled yield that multi-step processes actually deliver.
First-pass yield is the share of units that get through a step correctly without rework.
How the scrap rate and yield calculator works
First-pass yield is the share of units that get through a step correctly without rework. Rolled throughput yield multiplies those across every step, and that multiplication is the thing to understand about multi-step processes.
Ten steps at 99% each give 90.4%, not 99%. Twenty steps at 95% give 35.8%. Long processes are punishing in a way that looking at any single step never reveals, and it is why step-level quality figures reported in isolation are misleading.
The cost of scrap is also understated by the material figure alone. A unit scrapped at the last step has consumed every step's labour and machine time, so late-stage scrap costs several times what early-stage scrap does.
Formula: yield = good / started; rolled yield = product of step yields
Worked examples
| Inputs | First-pass yield | Note |
|---|---|---|
| 5,000 started, 140 scrapped, 260 reworked | 92% | first-pass 92% |
| Ten steps at 99% | 100% | rolled 90.4% |
| No rework | 97.2% | first-pass equals final yield |
FAQFrequently asked questions
What is first-pass yield?
The share of units that pass a step correctly first time, without rework. Rework counts against it.
What is rolled throughput yield?
The product of every step yield. Ten steps at 99% each give 90.4%, not 99%.
Why does a long process lose so much?
Because yields multiply. Twenty steps at 95% deliver under 36%, which no single step-level figure reveals.
Is rework as bad as scrap?
Cheaper in material but often worse in time, and it hides the underlying defect rate — which is why first-pass yield excludes it.
Where does scrap cost most?
At the last step, because the unit has already consumed every prior step's labour and machine time.
Where these figures come from
- Nakajima (1988) — Introduction to TPM — the origin of Overall Equipment Effectiveness and its six big losses
- Safe Work Australia — the national work health and safety body
Last checked: September 2026. Definitions follow standard operations-management practice; where plants commonly differ, the page says so.