I created grids (A1, A2....,B1,B2,...etc.) in print layout (main properties-grids).I I also use atlas. I display many points and I need to calculate location of every point within a page of atlas and a grid. It is simple to calculate location of a point within a page atlas, because atlas is driven by a grid layer. I don´t know how to simply calculate location of a point within a grid. On a picture below black line is atlas grid frame (overlapping), red line are grids created at prinprint layout