Drawing on the past methodological documents since 2010 for MPI-O and MPI-I, and on the global 2018 revision, this document provides a comprehensive guide to the methodology for estimating and reporting the global MPI in 2018. The methodology for the first global MPI by Alkire and Santos (2010) was documented in a working paper co-published by OPHI and HDRO. The underlying methodology, dimensions and number of indicators have remained unchanged since 2010. This document summarizes how the global MPI 2018 is computed. However, before moving to the specifics, we provide a brief intuitive introduction to the MPI and its linked partial and sub-indices, and clarify how a global MPI differs from official national poverty statistics.