Scrap rate is the percentage of manufactured units that fail quality standards and cannot be sold or reworked into a good part. It measures wasted material, labor, and machine time as a share of total production, making it one of the clearest signals of process quality on a factory floor.
Scrap rate is a simple ratio expressed as a percentage. Use this formula:
Worked example: a line runs 10,000 parts in a shift. Quality control rejects 320 as unrecoverable defects. The calculation is (320 / 10,000) x 100 = 3.2% scrap rate. If you instead measure by cost, replace unit counts with the value of scrapped material and labor. A 3.2% rate on a part costing 12 euros in materials and processing means roughly 3,840 euros of loss per 10,000 units, before you even count the lost capacity.
Scrap rate and yield describe the same process from opposite directions, so it helps to track both. Yield is the share of production that passes as good; scrap rate (plus rework, where it applies) accounts for what does not.
A clean quality picture needs all three numbers: yield, rework rate, and scrap rate. Together they tell you not just how much you lose, but where the loss becomes permanent.
Scrap almost always traces back to a controllable process variable, not bad luck. The most frequent drivers cluster into a handful of categories:
Reducing scrap is a structured improvement loop, not a one-off cleanup. A practical sequence works best:
Programs such as Total Productive Maintenance tie these steps together by making operators and maintenance jointly accountable for equipment that runs clean.
Scrap rate feeds directly into the Quality component of Overall Equipment Effectiveness. OEE multiplies three factors: Availability, Performance, and Quality. The Quality factor is the ratio of good parts to total parts produced.
Example: with a 3.2% scrap rate, the Quality factor is 96.8%. If Availability is 90% and Performance is 95%, then OEE = 0.90 x 0.95 x 0.968 = 82.8%. Cutting scrap from 3.2% to 1.0% lifts Quality to 99% and pushes OEE to roughly 84.6%, a direct, measurable gain from a single quality improvement. Because the three factors multiply, scrap reduction compounds with availability and speed gains rather than competing with them.
Scrap rate is only useful when it drives a decision fast enough to matter. That means capturing defects at the source and connecting them to the equipment that caused them. Real-time production monitoring and computer-vision inspection can flag a rising defect trend on a specific machine, while a CMMS turns that signal into a maintenance work order before the next lot is ruined. Closing this loop, detect, diagnose, fix, verify, is what separates factories that report scrap from factories that reduce it.
A good scrap rate depends heavily on the industry and process complexity. Many discrete manufacturers target under 1% to 3%, while high-precision or high-mix operations may accept more. The more useful benchmark is your own trend: a scrap rate that falls steadily over time and stays stable shift to shift signals a process under control.
No. Scrap rate counts only unrecoverable units that are discarded. Parts that fail inspection but are reworked into good units are tracked separately as rework or rejected-at-first-pass. Keeping scrap and rework distinct matters because rework consumes labor and capacity without showing up in scrap numbers, so measuring both prevents a hidden cost from going unnoticed.
Scrap rate lowers the Quality factor of OEE, which is calculated as good parts divided by total parts produced. With no rework, Quality equals one minus the scrap rate. Because OEE multiplies Availability, Performance, and Quality, every point of scrap you eliminate raises the Quality factor and lifts overall OEE proportionally.
Book a Fabrico demo to see how real-time OEE monitoring and integrated CMMS work orders help you catch rising scrap at the machine and turn defect data into fewer wasted parts.
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