Abstract We present new features of the FeynRules and MadGraph 5_aMC@NLO programs for the automatic computation of decay widths that consistently include channels of arbitrary final-state multiplicity. The implementations are generic enough so that they can be used in the framework of any quantum field theory, possibly including higher-dimensional operators. We extend at the same time the conventions of the Universal FeynRules Output (or UFO) format to include decay tables and information on the to... Title of program: MadWidth Catalogue Id: AEXY_v1_0 Nature of problem The program is a module for the FeynRules and MadGraph5_aMC@NLO packages that allows the computation of tree-level decay widths for arbitrary BSM models. The module consists of two parts: A FeynRules part, which allows one to compute analytically all tree-level two-body decay rates and to output them in the UFO format. A MadGraph5_aMC@NLO part, which allows the numerical computation of many-body decay rates. Versions of this program held in the CPC repository in Mendeley Data AEXY_v1_0; MadWidth; 10.1016/j.cpc.2015.08.031 This program has been imported from the CPC Program Library held at Queen's University Belfast (1969-2018)