How to Get the Cake Board the Right Size for the Cake
Cake boards can be purchased in a variety of shapes and sizes at cake decorating supply stores or craft stores. Cakes baked in shaped pans can be placed on large cake boards or you can trim the cake board so that it is the exact same size as any cake.
Purchase cardboard cake boards larger than the cake you plan to bake; they can be cut easily with scissors.
Place the cake pan you are using onto a cardboard cake board that is slightly larger than the pan.
Trace around the pan with a pencil. Remove the pan from the cake board.
Measure about 1 inch from the pattern of the cake pan. Draw a new line to create a 1-inch border around the cake pan pattern.
Cut the cake board with scissors along the outer set of pencil lines.
Place the baked cake directly onto the centre of the cake board. You should have 1 inch of board extending from the cake to make transporting the cake easier.