The invention relates to a container (1) for a fluid for metering a reagent into a microfluidic system. The container comprises a chamber (4) and a first film (3) which seals off the chamber (4) so that the fluid is encapsulated in the chamber. Advantageously, the first film (3) is an aluminum sealing film. A second film (7) is sealingly arranged on the first film, for example by adhesive bonding of the film layers. The films differ in their tear strength such that when pressure is applied simultaneously to both films the first film tears while the second film deforms elastically and/or plastically. By tearing the first film a connection is produced between the container chamber and an inlet channel so that a fluid contained in the chamber flows into the microfluidic system.