Abstract: A kraft paper having a pulp according to ISO 536 of between 60 g/m2 and 120 g/m2, a density of between 680 kg/m3 and 720 kg/m3, and a tensile strength index in the machine direction according to ISO 1924-3 of between 79 kNm/kg and 98 kNm/kg, the kraft paper optionally having a coating and/or an auxiliary element on at least one side. The kraft paper is made of a pulp having an average pulp fibre length of 2.2 mm to 2.7 mm with a minimum pulp content of at least 96% wt. %; a pore volume of the uncoated kraft paper is between 200 ?l/g and 220 ml/g; in the thickness direction of the paper, there are regions of different porosities; and at least one region has pores with a pore diameter of less than or equal to 0.3 ?m. The invention also relates to a paper sack.