Standard counter top depth is 25" on standard base cabinetry (24" deep). However your base cabinets determines the depth ... I.E. a standard vanity cabinet is 21" deep so the standard vanity top is 22" deep. If you aren't putting the top on cabinetry and it will just be floating you are flexible to do whatever works best for your room. We have many clients that go with deeper floating counter tops (27-30") in the laundry room so they have more area to fold laundry at and can store hampers and laundry baskets below. Hope that helps, good luck with your project!