This document provides an overview of key performance indicators (KPIs) used to measure maintenance performance. It defines 17 primary maintenance KPIs including lost time injury frequency rate, maintenance cost per unit, maintenance effectiveness, mean time between failure, and percentage of failures investigated. For each KPI, the document provides the formula, how to interpret higher or lower values, and whether they indicate effective or ineffective maintenance practices. The goal is to improve understanding of KPIs and how personnel can influence maintenance performance.