Fringing intertidal flats are common features of elongated estuaries. We generalized the geometry of profiles of individual intertidal flats towards a common relationship, based on extensive measurement data of various estuaries. We found a strong linear relation between the width, slope and height of linear intertidal flat profiles, which also yields well for the mild-sloped upper part of convex-up profiles. Deviations of this linear relation at the lower steeper part of the flats are the result of dominating alongshore currents.