Abstract: The drainage pipe slope measuring device includes a housing having an upper surface and a lower surface. The upper surface has an opening formed therethrough, the lower surface preferably having a substantially concave or arcuate cross-sectional contour adapted for flush mounting against the drainage pipe. A spirit level vial is mounted within the housing and is positioned adjacent the opening. The vial is preferably formed from at least partially transparent or translucent material and is adapted for containing a liquid and a gas bubble. Indicia is formed on the container and is visible through the opening so that, when the housing is mounted on the drainage pipe, a position of the gas bubble with respect to the indicia provides the user with a visual indication of the slope of the drainage pipe. The vial is preferably divided into separately colored regions to provide the user with further visual contrast.