How to Calculate Non-conformance Rate

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Non-Conformance Rate Calculator

Non-Conformance Rate (NCR) Calculator

The total number of items produced or checked in the batch.
The number of items that failed to meet quality standards.
$
Enter production cost to estimate financial loss.

Calculation Results

Non-Conformance Rate 0.00%
Conformance Rate (Yield) 0.00%
Parts Per Million (PPM) 0
Estimated Cost of Non-Quality (Internal Failure Cost) $0.00
Please enter valid numbers. Defective units cannot exceed total units inspected.

How to Calculate Non-Conformance Rate

The Non-Conformance Rate (NCR) is a critical Key Performance Indicator (KPI) used in quality management, manufacturing, and supply chain logistics. It measures the proportion of a product batch or service instances that fail to meet pre-defined quality standards or specifications.

Monitoring your NCR allows you to identify process inefficiencies, reduce waste, and minimize the Cost of Poor Quality (COPQ). A high non-conformance rate typically indicates issues with raw materials, machine calibration, or operator training.

Non-Conformance Rate Formula

The calculation for non-conformance is straightforward. It compares the number of defective units found against the total number of units inspected.

NCR (%) = (Total Defective Units / Total Units Inspected) × 100

Where:

  • Total Defective Units: The count of items that have critical, major, or minor defects (depending on your acceptance criteria).
  • Total Units Inspected: The total sample size or production batch size checked.

Calculation Example

Imagine a factory produces 12,500 plastic widgets in a single shift. During quality control inspection, the QA team discovers that 275 widgets are warped or cracked.

To calculate the rate:

  1. Divide the defects by the total: 275 / 12,500 = 0.022
  2. Multiply by 100 to get the percentage: 0.022 × 100 = 2.2%

This means the Non-Conformance Rate is 2.2%, and the Conformance Rate (First Pass Yield) is 97.8%.

Why is NCR Important?

  • ISO 9001 Compliance: Tracking non-conforming outputs is a mandatory requirement for maintaining ISO certification.
  • Cost Reduction: Every non-conforming unit represents wasted material, labor, and energy.
  • Vendor Assessment: NCR is often used to grade suppliers. If a supplier consistently delivers a high rate of non-conforming parts, they may be replaced.

Interpreting the Results

While "zero defects" is the ultimate goal, acceptable NCR thresholds vary by industry. In Six Sigma methodologies, the goal is often 3.4 defects per million opportunities (DPMO). In general manufacturing, a rate below 1% is often considered excellent, while anything above 2-3% may trigger a Corrective and Preventive Action (CAPA) investigation.

function calculateNCR() { // Get Input Values var totalEl = document.getElementById('total_inspected'); var defectsEl = document.getElementById('total_defects'); var costEl = document.getElementById('cost_per_unit'); var resultBox = document.getElementById('ncr_results'); var errorBox = document.getElementById('ncr_error'); var costBox = document.getElementById('cost_result_box'); var total = parseFloat(totalEl.value); var defects = parseFloat(defectsEl.value); var costPerUnit = parseFloat(costEl.value); // Reset display resultBox.style.display = 'none'; errorBox.style.display = 'none'; costBox.style.display = 'none'; // Validation Logic if (isNaN(total) || isNaN(defects)) { errorBox.innerHTML = "Please enter valid numbers for Total Units and Defects."; errorBox.style.display = 'block'; return; } if (total <= 0) { errorBox.innerHTML = "Total Units Inspected must be greater than zero."; errorBox.style.display = 'block'; return; } if (defects < 0 || total total) { errorBox.innerHTML = "Error: Defective units (" + defects + ") cannot be greater than Total Units (" + total + ")."; errorBox.style.display = 'block'; return; } // Calculations var ncrRate = (defects / total) * 100; var yieldRate = 100 – ncrRate; // PPM Calculation (Parts Per Million) = (Defects / Total) * 1,000,000 var ppm = (defects / total) * 1000000; // Update DOM document.getElementById('result_ncr').innerHTML = ncrRate.toFixed(2) + '%'; document.getElementById('result_yield').innerHTML = yieldRate.toFixed(2) + '%'; document.getElementById('result_ppm').innerHTML = Math.round(ppm).toLocaleString(); // Optional Cost Calculation if (!isNaN(costPerUnit) && costPerUnit > 0) { var totalLoss = defects * costPerUnit; document.getElementById('result_cost').innerHTML = '$' + totalLoss.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}); costBox.style.display = 'block'; } // Show Results resultBox.style.display = 'block'; } function resetNCR() { document.getElementById('total_inspected').value = "; document.getElementById('total_defects').value = "; document.getElementById('cost_per_unit').value = "; document.getElementById('ncr_results').style.display = 'none'; document.getElementById('ncr_error').style.display = 'none'; }

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