Reject Rate Calculation

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Reject Rate Calculator

Production Metrics

Reject Rate: 0%
Yield Rate: 0%
Financial Loss: $0.00
function calculateRejectRate() { var total = parseFloat(document.getElementById('totalUnits').value); var rejected = parseFloat(document.getElementById('rejectedUnits').value); var cost = parseFloat(document.getElementById('unitCost').value); var resultArea = document.getElementById('rejectResultArea'); var costRow = document.getElementById('costImpactRow'); if (isNaN(total) || isNaN(rejected) || total total) { alert("Rejects cannot exceed total units inspected."); return; } var rate = (rejected / total) * 100; var yield = 100 – rate; document.getElementById('rejectPercentage').innerText = rate.toFixed(2) + "%"; document.getElementById('yieldPercentage').innerText = yield.toFixed(2) + "%"; if (!isNaN(cost) && cost > 0) { var loss = rejected * cost; document.getElementById('financialLoss').innerText = "$" + loss.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}); costRow.style.display = 'flex'; } else { costRow.style.display = 'none'; } resultArea.style.display = 'block'; }

Understanding the Reject Rate Calculation

In manufacturing and quality control (QC), the reject rate is a critical Key Performance Indicator (KPI) used to measure production efficiency and material quality. It represents the percentage of units that fail to meet quality standards compared to the total number of units inspected.

The Reject Rate Formula

To calculate the reject rate manually, you can use the following formula:

Reject Rate = (Total Rejected Units / Total Inspected Units) x 100

Why Tracking Reject Rates Matters

  • Cost Reduction: High reject rates indicate wasted raw materials and energy, directly impacting your bottom line.
  • Process Optimization: Frequent rejects in a specific batch often point toward machinery malfunctions or employee training gaps.
  • Customer Satisfaction: Lowering your reject rate ensures that fewer defective products reach the end consumer, protecting your brand reputation.
  • Supply Chain Transparency: Tracking rejects from specific suppliers helps in evaluating the quality of incoming raw materials.

Practical Example

Imagine a textile factory that produces 10,000 t-shirts. During the quality inspection phase, the QC team finds 250 shirts with stitching errors or fabric holes.

Using the formula:

  • Total Units: 10,000
  • Rejected Units: 250
  • Calculation: (250 / 10,000) * 100 = 2.5%

In this scenario, the Reject Rate is 2.5%, and the First Pass Yield (FPY) is 97.5%.

How to Improve Your Reject Rate

If your calculation shows a rate higher than the industry standard (which varies by sector, but often targets below 1-2%), consider these steps:

  1. Preventative Maintenance: Regularly service production equipment to prevent mechanical drift.
  2. Standard Operating Procedures (SOPs): Ensure all operators are following the exact same steps for every batch.
  3. Environmental Controls: Monitor temperature and humidity if your materials are sensitive to atmospheric changes.
  4. Root Cause Analysis (RCA): Use tools like the "5 Whys" or Ishikawa diagrams to find out exactly why defects are occurring.

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