Three methods to measure the in-plane permeability have been compared by theoretical analysis and repeated measurements. Based on this comparison the saturated parallel flow technique is suggested for continued evaluation. The stability of this method is better than 1%. However when doing repeatable measurements with new samples the averaged standard deviation increases to 14 % and 20 % for the two fabrics tested. By a round-robin comparison at three laboratories it is found that the reproducibility of the saturated parallel flow technique is in the same range as the repeatability of the method. It is clear that the scatter is due to the sample preparation, variations in the material and the method of loading the sample. Accordingly, a continued work should be concentrated on improvements of the sample preparation, and developments of methods to reduce the influence, from small errors, in sample preparation and sample loading on the results.