The calendar also features plenty of grid space for marking appointments, special occasions and events, and other notes. Classic square format. Updated style. Our square 18-month wall calendars include 13 stunning images and even clearer grids and text. Each of these 12 x 12 calendars features an opening spread with a beautiful six-month (July-December 2017) calendar to plan the last six months of the year and rev up for 2018. Filled with an abundance of holidays, each months grid is large enough for daily tasks and appointments.