A metering device for granular material, includes a housing that can be arranged inside a container for the granular material. The housing has at least one inlet for the granular material and an outlet, which outlet can be closed by a sealing element. The sealing element is arranged on a metering piston, which is preloaded by a spring and can be moved axially in a compressed-air cylinder, wherein a compressed-air connection is provided on the compressed-air cylinder such that the metering piston can be moved against the spring by compressed air and the outlet can be opened, and the spring has an at least two-stage design such that the stroke of the metering piston can be changed at least in two stages by varying the compressed air.