Overall Equipment Effectiveness: A measurement of total productive maintenance (TPM) that quantifies how efficiently equipment is used. OEE is derived from three factors: The availability rate calculates the percentage of scheduled time lost due to equipment breakdowns and changes. The operating speed losses-running at rates slower than the design speed and brief stops-are measured by the performance rate. The quality rate calculates the percentage of the total parts run that are lost to scrap and rework. OEE is calculated by multiplying those three components. Each one presents numerous improvement opportunities. The six primary losses, or failures, modifications, small stoppages, lower operating speeds, and scrap, are often the focus of OEE but some businesses also include other measures they deem significant.