What Thickness Should Cabinet Shelves Be?
Shelf sag is one of the most common complaints about stock cabinetry, and it comes down to two numbers: how thick the shelf is and how far it spans without support.
The general rule
Use 3/4" plywood for any shelf spanning up to about 32 inches under normal kitchen loads. Below 24 inches, 5/8" is usually acceptable. Half-inch particleboard shelves — common in budget cabinets — will visibly bow under a stack of dinner plates within a couple of years.
- Up to 24" span: 5/8" plywood minimum, 3/4" preferred
- 24"-36" span: 3/4" plywood
- Over 36" span: 3/4" plywood plus a center support or a hardwood edge band
Edge banding does more than look good
A 3/4" or 1-1/2" solid hardwood strip glued to the front edge of a shelf works like a beam and dramatically increases stiffness. It is the cheapest way to add span capacity without going to thicker plywood.
Pantry and bookcase shelves
Pantry shelves carry canned goods, which are far heavier per foot than dishes. For pantries and built-in bookcases, keep spans under 32 inches or add a vertical divider in the middle of the run.
The short answer
Specify 3/4" plywood shelves with a solid-wood front edge and keep unsupported spans under about 32 inches.