A metric is any quantifiable and measurable aspect of a process. A KPI, however, is a measure of the performance of a process over time. A metric counts occurrences of a process in time, whereas a KPI is goal-oriented, indicating the performance of the metric(s) it is based on. For example, the value of completed sales over a time period is a metric., whereas the value of completed sales over a time period divided by the value of inventory at the end of the period is a KPI.