How is the composite defect rate calculated?

Divide defects found by parts or features inspected, then multiply by 100. Eleven defects across 240 inspected parts give 11 ÷ 240 × 100, which is 4.58%.

What does a negative headroom mean?

The rate ran above your target. Headroom is target minus rate, so a 3% target against a 4.58% rate returns −1.58 points and the scope exceeded the allowed rate.

Can defects outnumber inspected parts?

Yes, when one part carries several findings. This page warns about that case rather than blocking it, because a delaminated panel can show more than one rejectable feature.

Which units belong in the inspected count?

Use the same basis as the defect count. Count whole parts if you accept or reject parts, or features such as plies and bond lines if findings are logged per feature.

Composites, Fiberglass & Advanced Materials calculator

Composite Defect Rate Calculator

Turn inspection counts into a defect rate and compare it with the target you enter. The inspected parts per defect shows how often one finding appears across the scope.

What this calculator does

Defect rate across inspected composite parts or features, with the gap to your target and the inspected count per defect.

Formula used

Defect rate (%) = defects found ÷ inspected parts or features × 100
Headroom to target (points) = target defect rate − defect rate
Inspected per defect = inspected parts ÷ defects found, blank when no defects are found

Inputs explained

Defects Found: Rejectable findings in the scope, counted at one level.
Parts or Features Inspected: Parts or features checked in the same scope and period.
Target Defect Rate: Control-plan, customer or historical target for this scope.

How to use the result

Best suited to trending a shift or build batch, reporting against a customer target, comparing two layup teams.
A rate hides severity, since one delamination and one cosmetic flaw count the same. Part-level and feature-level counts give rates that are not comparable.

Current U.S. benchmarks

The producer price index for plastic resins and materials stands at 280.569 (BLS, Aug 2026), up 6.6% from a year earlier. Quotes priced off last quarter's material cost miss this move.
Steel mill PPI stands at 381.162 (BLS, Aug 2026), up 23.4% from a year earlier. New factory orders are up 8.5% year over year (Census).

Common questions

How is the composite defect rate calculated? Divide defects found by parts or features inspected, then multiply by 100. Eleven defects across 240 inspected parts give 11 ÷ 240 × 100, which is 4.58%.
What does a negative headroom mean? The rate ran above your target. Headroom is target minus rate, so a 3% target against a 4.58% rate returns −1.58 points and the scope exceeded the allowed rate.
Can defects outnumber inspected parts? Yes, when one part carries several findings. This page warns about that case rather than blocking it, because a delaminated panel can show more than one rejectable feature.
Which units belong in the inspected count? Use the same basis as the defect count. Count whole parts if you accept or reject parts, or features such as plies and bond lines if findings are logged per feature.

Last reviewed 2026-10-01.