Abstract: A measuring arrangement for a wind power installation for determining a thrust force of the rotor. A measuring device detects a first bending moment of the tower at a first height and a second bending moment of the tower at a second height, which is different from the first height. The first and second bending moments are in this case made up in each case of a natural moment component, a pitching moment component and a thrust force component. A thrust force determining unit determines a thrust force of the rotor based on a comparison of the at least first and second bending moments, so that the natural moment component and the pitching moment component cancel one another out.