Measuring the branching ratio of h → μ⁺μ^- at the International Linear Collider

After the discovery of a Higgs boson at the LHC, the precise characterization of this particle is one of the most important topics in particle physics. Any deviation from the Standard Model (SM) prediction of its properties would indicate the existence of physics beyond the SM. In this talk, we present the prospects measuring the branching ratio of h → μ⁺μ^- at the International Linear Collider (ILC). The focus is a new study in full, Geant4-based detector simulation assuming 4 ab^-1 at 500 GeV, as foreseen in the official running scenario. The result is discussed in the context of projections for operating the ILC at 1 TeV, as well as for the HL-LHC.