In this study, the magnetocaloric effect in Ni50-xCuxMn38Sn12B3 ribbons depending on Cu substitution (x = 0, 1, 3) was investigated. The martensitic transition (MT) temperature of the ribbons shifted to lower temperatures with increasing Cu content. An inverse giant magnetocaloric effect (IMCE) was observed around the MT. Furthermore, the MT temperature of the x = 0 parent ribbon is around room temperature, which is important for technological applications. The Cu substitution helped to tune magnetization difference Delta M and hence the IMCE. The highest inverse magnetic entropy change Delta S-M(max) and the refrigerant capacity RC was obtained in the x = 1 Cu substituted ribbon. It is found that the inverse magnetic entropy changes Delta S-M were dependent on the thermal hysteresis. The average hysteresis losses (AHL) determined during cooling and heating processes were extremely different, indicating that the AHL is also thermal hysteresis dependent.