How do you calculate harness defect rate?

Divide the number of defective harnesses by the total harnesses built, then multiply by 100. With 8 rejects out of 250 built, that is 8 ÷ 250 × 100 = 3.2%.

What is a good defect rate for wire harness assembly?

Mature manual harness lines commonly run 1–3% at final test, with automotive and aerospace programs pushing toward well under 1%. At 3.2% you are at the high edge of typical and worth investigating.

Is defect rate the same as first-pass yield?

They are complements. A 3.2% defect rate means a 96.8% first-pass yield. Yield counts what passed; defect rate counts what failed.

Why is the gap to target 91.8 points here?

The tool subtracts your target (95) from the raw defect rate (3.2), giving -91.8; shown as magnitude it reads 91.8 points. If your target is meant as a yield goal, compare 96.8% yield to the 95% target instead.

How many harnesses should I sample to trust the rate?

With small lots, one defect swings the rate hard — 8 of 250 is 3.2% but 9 of 250 is 3.6%. Roll several lots together before reacting to a single shift's number.

What causes most wire harness defects?

Crimp height and pull-force failures, wrong terminal insertion, missed seals or boots, and circuit continuity errors from swapped leads dominate most harness Pareto charts.

Wire Harness, Cable & Electromechanical Assembly calculator

Harness Defect Rate Calculator

Harness defect rate is the percentage of wire harnesses that fail continuity, pull-test, or visual inspection out of everything built in a run. Quality engineers and line leads on wire-harness assembly cells track it as their primary yield signal because a crimp, a mis-inserted terminal, or a swapped circuit rarely shows up until final test. Watching this number shift day to day tells you whether an operator, a crimp die, or an incoming wire lot has gone out of spec before the escapes reach your customer. It is the single cleanest gauge of build quality on a harness line.

What this calculator does

Estimate harness defect rate for wire harness, cable and electromechanical assembly using production-ready inputs so teams can track KPI performance and decide whether corrective action is needed.
Use it when harness defect rate in wire harness, cable and electromechanical assembly needs a clean rate and gap-to-target you can put on a tier board.
It computes the percent of harnesses that failed inspection out of the total built, plus how far that sits from your yield target.

Formula used

Harness defect rate = harness defect rate count ÷ total harness defect rate population × 100
Harness defect rate gap to target = harness defect rate - target harness defect rate

Inputs explained

Harnesses failing inspection or continuity test:
Harnesses built and inspected in the run:
First-pass yield target for the line:

How to use the result

Use it at the end of a shift or a build lot to convert raw reject counts into a comparable rate and check it against your quality goal.
A raw defect rate treats every failure equally — a cosmetic label defect and a shorted circuit both count as one, so pair it with a Pareto of defect types before acting.

Current U.S. benchmarks

The producer price index for copper and brass mill shapes stands at 559.593 (BLS, May 2026), up 76.8% from a year earlier. Quotes priced off last quarter's material cost miss this move. Global copper trades at $13,484 per tonne (IMF via FRED, May 2026).
Manufacturing hourly earnings average $30.27 (BLS, Jun 2026), up 4.4% from a year earlier. Median machinist pay is $28.24/hr (OEWS 2025), with state medians on each state page. Manufacturers have 529k open positions nationally (BLS JOLTS).
The U.S. has 5,397 electrical equipment and appliances establishments employing about 369,437 workers (Census County Business Patterns, 2023).

Common questions

How do you calculate harness defect rate? Divide the number of defective harnesses by the total harnesses built, then multiply by 100. With 8 rejects out of 250 built, that is 8 ÷ 250 × 100 = 3.2%.
What is a good defect rate for wire harness assembly? Mature manual harness lines commonly run 1–3% at final test, with automotive and aerospace programs pushing toward well under 1%. At 3.2% you are at the high edge of typical and worth investigating.
Is defect rate the same as first-pass yield? They are complements. A 3.2% defect rate means a 96.8% first-pass yield. Yield counts what passed; defect rate counts what failed.
Why is the gap to target 91.8 points here? The tool subtracts your target (95) from the raw defect rate (3.2), giving -91.8; shown as magnitude it reads 91.8 points. If your target is meant as a yield goal, compare 96.8% yield to the 95% target instead.
How many harnesses should I sample to trust the rate? With small lots, one defect swings the rate hard — 8 of 250 is 3.2% but 9 of 250 is 3.6%. Roll several lots together before reacting to a single shift's number.

Last reviewed 2026-05-12.