-As the bracket covers the edge of the shelf, you can cut the shelf without the cut edge showing.
Good to know
Mount the brackets with a maximum distance of 31½" between them to ensure the wall shelf is as stable as possible. Different wall materials require different types of fasteners. Use fasteners suitable for the walls in your home. If you are uncertain about what type of mounting devices to use, please contact your local hardware store. Also available in size 31⅛x7½".
As the bracket covers the edge of the shelf, you can cut the shelf without the cut edge showing. https://www.ikea.com/us/en/images/products/ekby-tony-ekby-bjarnum-wall-shelf-white__0302415_PE427047_S4.JPGEKBY TONY / EKBY BJÄRNUM Wall shelf, high gloss white, aluminumhttps://www.ikea.com/us/en/catalog/products/S69048170/690.481.70IKEA$36.99