Floor panel for forming a floor covering, wherein this floor panel is realized substantially on the basis of synthetic material and preferably as a layer-shaped substrate; wherein this floor panel is of the supple type and is rectangular, either oblong or square, and thus comprises a first pair of opposite edges (2-3) and a second pair of opposite edges (4-5); wherein both pairs of opposite edges (2-3, 4-5) comprise coupling parts (6-7, 8-9) which allow mutually coupling a plurality of such floor panels to each other; wherein said coupling parts (6-7, 8-9), on both pairs of edges (2-3, 4-5), form a first locking system which, in a coupled condition of two of such floor panels, effects a locking in the plane of the floor panels and perpendicular to the respective edges, as well as form a second locking system, which, in a coupled condition of two of such floor panels, effects a locking transverse to the plane of the floor panels; wherein these coupling parts (6-7) on the first pair of opposite edges substantially are realized in the material of the floor panel itself and more particularly in said substrate; wherein the coupling parts of at least the first pair of opposite edges (2-3) are configured such that two of such panels can be coupled to each other at these edges by means of a turning movement, and to this aim these coupling parts (6-7) on the first pair of opposite edges consist of a tongue and a groove as well as of locking parts (12-13) which, in the coupled condition, prevent the shifting apart of the tongue and groove; and wherein, on the first pair of opposite edges, the groove is bordered by a lower lip and an upper lip , of which the lower lip extends laterally to beyond the distal end of the upper lip; wherein the floor panel has an overall thickness (T) which is smaller than or equal to 4.5 millimeters; characterized in that the locking parts of the first pair of opposite edges have a locking distance (A) which is greater than 0.6 times the value of the overall thickness (T) of the floor panel, wherein the locking distance (A) is formed by the horizontal distance between the vertical closing plane (S) of two coupled floor panels and a vertical plane (VS) through the middle of the zone over which the locking surfaces of the locking parts, in coupled condition, make contact with each other, as measured in horizontal direction, and wherein the closing plane (S) is defined as a vertical plane through the most distal end of the upper lip ; and the upper side of the lower lip at the height of said closing plane, in the coupled condition of two of such panels, is located on a level (N1) which is situated higher than the level (N2) which is determined by the lowermost point of the locking part located on the underside of the tongue, wherein the height difference between the two levels (N1 and N2) is at least 0.05 times the overall thickness (T); and that the first pair of opposite edges is configured such that, when two of such floor panels are coupled to each other, a contact, herein below named first contact (C1), is present between the underside of the tongue and the upper side of the lower lip, wherein the contact point or contact zone defined by such first contact (C1), seen in cross-section, is situated entirely within two planes (V1 and V2) which are located parallel to the closing plane (S), this respectively on both sides of this closing plane, each time one millimeter remote from this closing plane (S), or still better each time half a millimeter remote therefrom; such that, in other words, the first contact (C1) is locally present between said planes (V1 and V2) and thus does not continue beyond these borders. <EOS>