Abstract: Device for determining the quantity of the contents of a tank (1) mounted in a frame (3,4) which rests on a base with four points of support disposed in the corner points of a rectangle, two adjacent points of support being constituted by force measuring elements (6) each consisting of a generally block-shaped body (7) of metal, in which an opening (8) is cut out such that at the lower and upper sides of the body two relatively thin elongated and substantially horizontally extending portions (9,10) are formed which are connected to each other at both ends by thicker material portions disposed at the vertical sides of the body, whereas at the lower side of the body a foot (11) is formed which protrudes from one vertical side towards the vertical axis of the body, and with which the body rests on the base, and the supporting frame (3,4) of the tank is affixed on the upper side of the body near its other vertical side, and two strain gauges (T1,T2) aligned in spaced apart relation with each other in the directio