An island fails in one of two ways: it is too small to do anything, or it is big enough that nobody can get past it. Both are decided by clearances, and both are fixable on paper.
Start with the gaps, not the island
The island is whatever is left once the circulation works. In practice that means:
- 900mm minimum between the island and any run of cabinetry. This is the absolute floor and it feels tight the moment two people are in the room.
- 1000–1200mm is the comfortable range, and what we draw by default.
- 1200mm+ on the side where the dishwasher or oven opens, because a person has to stand behind an open door.
- Over about 1400mm, a kitchen starts to feel like walking rather than working. Bigger is not better.
Measure those gaps from the finished face of the door, not the carcass. Handles, a proud fridge and a skirting board all eat into the number you drew.
Seating, and the overhang nobody allows for
If people are going to sit at the island, the worktop has to overhang far enough for their knees. 300mm of overhang is the working minimum; 350mm is comfortable. Anything less and everyone sits sideways.
Allow 600mm of width per seat, and decide early whether the overhang is supported. A stone top can cantilever only so far before it needs a bracket or a thicker section, which is a structural question, not a styling one, and it changes the price.
What the services decide
The moment an island carries a sink, a hob or both, the plumbing and extraction dictate where it can sit. Waste pipes need a fall, so the island position is constrained by where the drainage can reach, which on a slab is settled long before the kitchen is drawn.
Extraction over an island is the other big decision. A ducted downdraft or ceiling unit works far better than a recirculating one, but it has to be planned into the slab or the ceiling void early. Deciding this at installation is the most common expensive change we see.
A sensible default
For most homes with an open-plan living space, a good starting point is an island of roughly 2400 × 1100mm, with 1100mm clear on the working side, seating for three on the long side with a 350mm overhang, and the hob on the island only if extraction has been planned into the ceiling.
That is a default, not an answer. The answer comes from measuring your room, which is where we start.
