Abstract: Disclosed herein is a humidity calibrator device including a base part sealed by plugs, and a replaceable humidity calibrator cartridge. The cartridge contains saturated vapor, saturated salt solution and salt crystals. The cartridge is sealed with a semipermeable membrane and an air-tight protective peel-off foil. The semipermeable membrane, which seals the part of the humidity calibrator cartridge entering the base part of the apparatus provides a separation of the compartment in the base of the apparatus and liquid containing space of the cartridge, allowing permeation of water vapor and preventing permeation of the liquid.