Standard EN ISO 12957-2 involving an inclined plane device can be used to measure the interface friction angle between two layers of geosynthetics at low normal stresses. The principle of this standard increases shear stress until the interface slides. The main objective of this study was to compare this loading method with that of the shear box which increases displacement at a constant rate while recording shear stress. Two classical geosynthetic-geosynthetic interfaces were selected. The first one was a non-woven geotextile on a 2 mm thick HDPE geomembrane and the second one was geocomposite drainage on the same HDPE geomembrane. The two metric scale devices used were an inclined plane device and a shear box, and friction tests were conducted with the same normal stress of 5 kPa. The results show that the shear box test enables the determination of both peak and residual friction angles, which is not possible with the inclined plane test. In addition, friction angle results from the shear box test are more reliable than those from the inclined plane test.