Preheat the oven to 350°F (175°C) and lightly grease a 9×13-inch baking pan.
In a bowl, combine 2 cups graham cracker crumbs, 4 1/2 tablespoons granulated sugar, and 1/2 cup melted butter until the mixture is evenly moistened.
Press the crumb mixture firmly and evenly into the bottom of the prepared 9×13-inch pan to form the crust.
Bake the crust for 15 minutes, then remove from the oven.
While the crust bakes, stir together one 14-ounce can sweetened condensed milk and 2 cups flaked coconut in a bowl until combined.
Spread the coconut mixture evenly over the hot crust, return the pan to the oven, and bake for an additional 15 minutes, until the coconut layer is lightly browned.
Remove the pan from the oven. Drizzle 1 3/4 cups melted semisweet chocolate chips evenly over the coconut layer.
Allow the bars to cool until the chocolate hardens, about 1 hour, then cut into 24 squares.