Size dado width and depth for shelf pins, drawer bottoms, and back panels.
Cut a test dado in scrap first and check the fit — the shelf should slide in with hand pressure, no wobble. Use a router with a straight bit or a table-saw dado stack.
A dado is a rectangular groove cut across the grain; the same cut with the grain is called a groove. Both are sized the same way: width matches the panel going in, depth is about ⅓ the board thickness to preserve structural integrity.
A rabbet is an L-shaped step cut along the edge or end of a board — used for cabinet backs, drawer fronts, and case joinery. The rabbet depth is typically half the board thickness, or equal to the panel thickness for a flush-fitting back panel.
Plywood note: sheet goods are often 1/32″ undersize from the nominal dimension (a ¾″ sheet is commonly 23/32″). The plywood correction checkbox subtracts 1/64″ from the dado width to account for this, giving a snug fit without ripping the shelf.