Understanding Scrap Rate
How we calculate. Scrap % = scrap count ÷ total count × 100. See our methodology and accuracy policy .
Real-world scenario: A typical Scrap Rate case uses scrap units 8 and total units 800. Enter the same figures below to reproduce the worked path.
What is Scrap Rate?
A quality-cost KPI. Lower is better. Material scrap weight variants use the same structure with weight UOMs.
- Same UOM for scrap and total
- Define scrap vs rework
- Lower is better
The Formula
Worked Example
Common Use Cases
- Cost of poor quality: scrap trends
- Process capability: waste hotspots
- Material planning: yield loss
Pro Tips
- Separate startup scrap
- Track root causes
- Pair with yield rate
| Scenario | When to use |
|---|---|
| Percent of a number | Finding a part of a whole (tax, tip, score) |
| Percent change | Comparing old vs new values |
Limitations: Scrap Rate results are educational manufacturing and lean/TPM planning aids—not process-safety, quality-system, or financial advice. Confirm definitions with your MES/SCADA and quality policies.
Common mistakes
- Swapping part and whole: The denominator must be the full total, not a subset.
- Rounding too early: Carry extra decimal places through multi-step work before rounding the final percent.
- Mixing percent and decimal forms: Enter rates in the format the calculator labels expect.
The worked example for scrap rate was verified with the calculator form on this page—enter the same values to confirm the result.
When to use this calculator
- Use this page when your wording matches scrap rate and the form labels on screen.
- Use percent of a number for “what is X% of Y?” problems.
- Use number is what percent when you know part and whole and need the percent.
Still unsure about scrap rate? Start with the quick answer above, then open the linked calculator that matches your wording.
❓ Frequently Asked Questions
How do I use this scrap rate calculator?
For scrap rate, enter the values labeled on the form, then press Calculate. Compare the result to the worked example on this page.
What formula does this page use?
See the quick answer and formula box above for scrap rate—the same percentage calculator expression is applied to your inputs.
What if my result looks wrong?
When checking scrap rate, re-check part vs whole (or rate vs base), rounding, and whether percents were entered as 25 rather than 0.25 when the form expects percents.
Authoritative References
For OEE and manufacturing KPI definitions, consult: