Kitchen Island Dimensions: Height, Depth and Seating Space

The height matches the rest of the kitchen, so the island works as an extra countertop. The depth is a 23.5 in base cabinet plus the 12 to 16 in overhang that seated knees need. The length is the one measurement that is yours to choose, and it is easiest to choose it by counting the people who will sit there every day rather than the guests who come twice a year.

An island without seating can be as shallow as the cabinets themselves. Once people sit at it, the overhang is not optional: without it, knees hit the cabinet doors and everyone ends up sitting sideways.

In Swedish kitchens 35.5 in is the standard countertop height, and in the US it is 36 in, so an island that matches the kitchen almost always lands in the counter range.

The island height decides the stool height. Measure from the floor to the underside of the countertop, not the top, and keep 9 to 10 in between the seat and that edge: a 26 in seat for a counter-height island and a 30 in seat for a bar-height one. A thick stone top lowers the underside by several inches, which is why two islands of the same overall height can need different stools. The bar stool height guide has the full table.

The overhang is the part of the countertop that sticks out past the cabinets on the seating side. In our experience 10 in still works for short meals; below that, people turn sideways because their knees meet the cabinet doors. The US kitchen designers' association, the NKBA, gives a minimum of 15 in of clear knee space at counter height, which sits inside the same range.

A deeper island is not automatically better. Beyond about 39.5 in, the far side of the countertop gets hard to reach from the stools, and a top that deep usually needs a joint or a special order. If you want seating on two sides, plan the overhang on both. The island overhang guide covers supports and materials.

If people walk behind the stools, it becomes about 12.2 ft. Along the island, the length is the seating length from the table above plus a walkway of at least 36 in at each end you need to pass.

If the room comes up short, there are three good answers. A narrower island with seating on the end rather than the long side; a peninsula, which joins the cabinets and saves one walkway; or slim backless stools, which free up the floor behind the seats when nobody is sitting. Our guide to small kitchen islands works through each of them.

The underside height. The finished height minus the thickness of the top is what decides the stool. A stone top can be 0.75 to 2.5 in thick, enough to move you from one seat height to the next.

The overhang and its supports. Plan 12 to 16 in on the seating side. Whether it needs brackets or legs depends on the material and its thickness, and your countertop supplier's specification applies. Place any supports where they will not meet knees or armrests.

The knee zone. Keep the space under the overhang free of plinths, handles and doors that open towards the stools.

The seating length. Mark 21.5 in per stool on the floor with tape and sit there on a kitchen chair before you commit. It is the quickest test there is, and it shows straight away whether the room works.