Calculating Oee in Excel

Overall Equipment Effectiveness (OEE) Calculator

Total time the equipment was scheduled to operate (e.g., shift length).
Time the equipment was stopped due to breakdowns, changeovers, etc.
The fastest possible time to produce one unit.
The total number of units manufactured.
Units that did not meet quality standards and were rejected.

OEE Calculation Results:

Availability:

Performance:

Quality:

Overall Equipment Effectiveness (OEE):

function calculateOEE() { var plannedProductionTime = parseFloat(document.getElementById('plannedProductionTime').value); var totalDowntime = parseFloat(document.getElementById('totalDowntime').value); var idealCycleTime = parseFloat(document.getElementById('idealCycleTime').value); var totalUnitsProduced = parseFloat(document.getElementById('totalUnitsProduced').value); var defectUnits = parseFloat(document.getElementById('defectUnits').value); var resultDiv = document.getElementById('oeeResult'); var errorDiv = document.getElementById('oeeError'); resultDiv.style.display = 'none'; errorDiv.style.display = 'none'; errorDiv.innerHTML = "; // Input validation if (isNaN(plannedProductionTime) || plannedProductionTime <= 0) { errorDiv.innerHTML = 'Please enter a valid Planned Production Time (must be greater than 0).'; errorDiv.style.display = 'block'; return; } if (isNaN(totalDowntime) || totalDowntime plannedProductionTime) { errorDiv.innerHTML = 'Total Downtime cannot exceed Planned Production Time.'; errorDiv.style.display = 'block'; return; } if (isNaN(idealCycleTime) || idealCycleTime <= 0) { errorDiv.innerHTML = 'Please enter a valid Ideal Cycle Time (must be greater than 0).'; errorDiv.style.display = 'block'; return; } if (isNaN(totalUnitsProduced) || totalUnitsProduced < 0) { errorDiv.innerHTML = 'Please enter a valid Total Units Produced (cannot be negative).'; errorDiv.style.display = 'block'; return; } if (isNaN(defectUnits) || defectUnits totalUnitsProduced) { errorDiv.innerHTML = 'Defect Units cannot exceed Total Units Produced.'; errorDiv.style.display = 'block'; return; } // 1. Calculate Availability var operatingTime = plannedProductionTime – totalDowntime; var availability = (plannedProductionTime > 0) ? (operatingTime / plannedProductionTime) : 0; // 2. Calculate Performance var theoreticalMaxUnits = (idealCycleTime > 0) ? (operatingTime / idealCycleTime) : 0; var performance = (theoreticalMaxUnits > 0) ? (totalUnitsProduced / theoreticalMaxUnits) : 0; // Performance cannot exceed 100% if (performance > 1) { performance = 1; } // 3. Calculate Quality var goodUnits = totalUnitsProduced – defectUnits; var quality = (totalUnitsProduced > 0) ? (goodUnits / totalUnitsProduced) : 0; // 4. Calculate OEE var oee = availability * performance * quality; // Display results document.getElementById('availabilityResult').innerText = (availability * 100).toFixed(2) + '%'; document.getElementById('performanceResult').innerText = (performance * 100).toFixed(2) + '%'; document.getElementById('qualityResult').innerText = (quality * 100).toFixed(2) + '%'; document.getElementById('finalOEE').innerText = (oee * 100).toFixed(2) + '%'; resultDiv.style.display = 'block'; }

Understanding Overall Equipment Effectiveness (OEE)

Overall Equipment Effectiveness (OEE) is a critical metric used in manufacturing to measure how effectively a manufacturing operation is utilized. It provides a comprehensive view of how well your equipment is performing by breaking down its efficiency into three measurable components: Availability, Performance, and Quality.

What is OEE?

OEE is expressed as a percentage and is calculated by multiplying the three factors: Availability, Performance, and Quality. A perfect OEE score of 100% means that your manufacturing process is producing only good parts, as fast as possible, without any stop time.

OEE = Availability × Performance × Quality

The Three Pillars of OEE:

1. Availability

Availability accounts for all planned and unplanned stops. It measures the percentage of time that equipment is actually running compared to the time it was planned to run. Downtime events (e.g., breakdowns, changeovers, material shortages, maintenance) reduce availability.

Availability = (Operating Time / Planned Production Time)

  • Planned Production Time: The total time the equipment was scheduled to operate.
  • Operating Time: Planned Production Time minus any Downtime.
  • Total Downtime: The total time the equipment was not running when it should have been.

For example, if a machine is scheduled for an 8-hour shift (480 minutes) but experiences 60 minutes of downtime, its operating time is 420 minutes. Availability would be (420 / 480) = 0.875 or 87.5%.

2. Performance

Performance measures how fast the equipment is running compared to its ideal speed. It accounts for slow cycles (e.g., machine running slower than its ideal cycle time) and minor stops (e.g., brief pauses, idling, or jams).

Performance = (Total Units Produced / Theoretical Maximum Units)

  • Total Units Produced: The actual number of units produced during the operating time.
  • Ideal Cycle Time: The fastest possible time to manufacture one unit.
  • Theoretical Maximum Units: The number of units that *could* have been produced during the Operating Time if the machine ran at its Ideal Cycle Time (Operating Time / Ideal Cycle Time).

Continuing the example, if the operating time is 420 minutes and the ideal cycle time is 0.5 minutes/unit, the theoretical maximum units are (420 / 0.5) = 840 units. If only 700 units were actually produced, Performance would be (700 / 840) = 0.8333 or 83.33%.

3. Quality

Quality measures the percentage of good units produced compared to the total units produced. It accounts for defects and rework, ensuring that only products meeting quality standards are counted.

Quality = (Good Units / Total Units Produced)

  • Good Units: Total Units Produced minus Defect Units.
  • Defect Units: Units that do not meet quality standards and are rejected or require rework.

If 700 units were produced and 20 of them were defects, then 680 units were good. Quality would be (680 / 700) = 0.9714 or 97.14%.

Calculating OEE: A Combined Example

Using the values from our examples:

  • Availability = 87.5% (0.875)
  • Performance = 83.33% (0.8333)
  • Quality = 97.14% (0.9714)

OEE = 0.875 × 0.8333 × 0.9714 = 0.7083 or 70.83%.

This means that, overall, the equipment is operating at about 70.83% of its theoretical maximum potential, considering all losses.

Why is OEE Important?

OEE helps manufacturers:

  • Identify Losses: Pinpoint where productivity is being lost (e.g., too much downtime, slow production, high defect rates).
  • Benchmark Performance: Compare equipment performance over time or against industry standards.
  • Drive Continuous Improvement: Focus improvement efforts on the areas with the biggest impact on overall efficiency.
  • Increase Profitability: By optimizing equipment usage, companies can reduce costs, increase output, and improve customer satisfaction.

Use the calculator above to quickly determine your OEE score and gain insights into your manufacturing process efficiency.

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