Overall Equipment Effectiveness (OEE

Lean Manufacturing: Overall Equipment Effectiveness (OEE) & The Six Big Losses

Formulated by Seiichi Nakajima in the 1970s as a core pillar of Total Productive Maintenance (TPM), OEE is the gold standard for measuring manufacturing productivity:

• The Three Core Dimensions:

• Availability: Loss from unplanned machine breakdowns and prolonged changeovers/setups.

• Performance: Loss from running at reduced speeds and minor stoppages/idling.

• Quality: Loss from scrap defects, startup rework, and test reject parts.

• The Six Big Losses Framework:

• Equipment Breakdowns (Availability loss)

• Setup and Tool Adjustments (Availability loss)

• Small Stops / Jams under 5 mins (Performance loss)

• Reduced Machine Speed (Performance loss)

• In-Process Scrap & Defects (Quality loss)

• Startup / Warm-Up Yield Rejects (Quality loss)

• World-Class OEE Target (85%): Recognized globally as .

How to Use This Calculator

Enter your Total Shift / Schedule Duration (minutes) (e.g. 480 (8-hour shift)), Planned Breaks & Scheduled Maintenance (minutes) (e.g. 30 (Meal breaks, planned shift meetings)), Unplanned Downtime & Equipment Breakdowns (minutes) (e.g. 45 (Equipment failures, changeovers, jams)), Ideal / Nameplate Cycle Time (seconds/unit) (e.g. 1.20 (Theoretical fastest speed per part)), Total Units Produced (Good + Scrap / Rework) (e.g. 18,000), and Good Quality Conforming Units Produced (e.g. 17,460). Results update instantly as you type — adjust any value to compare scenarios.

The Formula

Overall Equipment Effectiveness (OEE) \& Total Productive Maintenance equations:

Planned Production Time (PPT) = Shift Duration - Planned Breaks

Operating Run Time = PPT - Unplanned Downtime

Availability (A) = (Operating Run Time) / (Planned Production Time)

Performance (P) = (Ideal Cycle Time × Total Units Produced) / (Operating Run Time)

Quality (Q) = (Good Conforming Units) / (Total Units Produced)

Overall Equipment Effectiveness (OEE) = Availability × Performance × Quality

Fully Productive Time = PPT × OEE

Worked Example

For example, evaluating an 8-hour shift (480 minutes) with 30 minutes of planned breaks mins), 45 minutes of unplanned machine breakdowns mins = 24,300 seconds), ideal cycle time 1.20 seconds/unit, 18,000 total units produced, and 17,460 good units: . . . Overall \ (Above Average benchmark).

Understanding Your Result

Evaluate your result in the context of your specific use case and relevant industry standards or reference values. A single calculated result is a starting point — test two to three scenarios to understand how sensitive the outcome is to your key input assumptions. For high-stakes decisions, verify your result against a secondary source or subject-matter expert before acting.