Kitchens come in all shapes and sizes, but the use of a central island has become an especially popular design feature. Islands may be as simple as a small, charming table that creates an interesting central element in the room. They can also be more complex features with plenty of storage, preparation surfaces, and even sinks or cooktops.

Islands play a key role in the modern use of the kitchen. Duo Dickinson, writing for This Old House, says older kitchen designs simply arranged the necessary appliances in an isolated, closed-off room. Newer kitchens are more open and inviting, and are often a place for residents and houseguests to congregate.

While kitchens were once based around the concept of a "work triangle"—which allowed a person to efficiently access the refrigerator, stove, and sink—they now typically have different food preparation areas to allow one or more cooks to work on a meal. An island is usually an essential part of this workflow, but only if there is enough space to move around it.

According to the home design site Apartment Therapy, the National Kitchen and Bath Association recommends leaving at least 42 inches of space between an island and an obstacle such as a counter or wall. If more than one person will regularly be in the kitchen, the recommended threshold is 48 inches.

You might also be able to fit an island into the kitchen with a smaller amount of clearance. Graeme Wilson, writing for the home design site Houzz, suggests that a separation of three feet is enough for multiple people to work in the kitchen while still allowing free travel.

It is also important that the various features of your kitchen can remain functional if an island is installed. The doors for your dishwasher, oven, and other appliances should have enough room to open fully. Drawers and cabinets should also be able to open without hitting an obstruction.

Dickinson says islands should be at least four feet wide and slightly more than two feet deep in order to be functional. For this reason, a kitchen should be at least 12 feet by eight feet in order for an island to feasibly be included.

The island should be at least 28 inches tall to accommodate a chair, and can be up to 48 inches tall in order to have barstool seating. For some kitchens, it may make the most sense to create an island with varying heights.

It is also possible to create a custom island for your kitchen. Wilson says you might shrink the depth of an island or change its shape to accommodate seating arrangements or provide enough room to fit adequately in a kitchen.

Apartment Therapy says islands are usually two to four feet in width. The minimum width is enough to fit a single 24-inch cabinet, and is best for kitchens where there is limited space.

Wilson suggests that islands should have a minimum size of 40 by 40 inches. This square island is enough to provide extra storage space, and can even be used for certain appliances. It also reduces the minimum recommended clearance to 31.5 inches, though this would be best suited for having only a single person in the kitchen.

Larger rooms can accommodate larger islands, but this is not always the best way to go. If an island is too big, it can inhibit traffic flow in the kitchen or make it seem too cramped.

Don't forget about access to the kitchen itself. Wilson says countertops will have a maximum size before a seam is necessary, and it may be difficult to get this piece into the room if it is only accessible through a narrow door or passageway.

If you don't think you have enough room for a permanent kitchen island, you can consider portable islands to use as needed. These options include lightweight butcher blocks or islands that have wheels. This feature adds extra storage capacity to the kitchen, but can also be easily moved if more space is needed.