Kitchen island size calculator

Find a size or check a proposal

If you are starting from an empty plan, choose Find my maximum size. Enter the room dimensions, the cabinet depths and the empty space you want to preserve on each side. The result is the largest rectangular worktop footprint left by those inputs. It is a geometric limit, not a recommendation to fill every available centimetre.

If you already have an island in mind, choose Check my island and enter its complete worktop width and length. The plan compares the four resulting gaps with your targets. Rotate the island to test its other orientation without retyping the measurements.

1. Measure the room. Use the narrowest usable wall-to-wall rectangle.
2. Account for fixed units. Choose a cabinet arrangement and adjust depths to include counters and fixed projections.
3. Choose your gaps. A working aisle, a walkway and a space behind seating can need different treatment.
4. Review the plan in use. Check entrances, appliance doors and people before developing the layout.

How the calculation works

All dimensions are calculated internally in centimetres. One inch equals exactly 2.54 cm; switching units preserves the underlying values. Displayed results are rounded to two decimal places.

For a proposed island, the tool first reserves the two target gaps on each axis, then shares any extra space equally between them. With equal targets the island is centred in the usable room. With different targets it moves towards the side needing less space. If the targets cannot all be reached, the placement stays inside the available room where possible and reports the shortfall.

For example, a 420 cm room with 60 cm of cabinets and a 90 cm island leaves 270 cm for its two side gaps. Targets of 120 and 90 cm use 210 cm; the remaining 60 cm is split equally, giving actual gaps of 150 and 120 cm. This is a placement rule for comparison, not an automatic choice of where an island belongs.

Try three measured examples

See the illustrated island scenarios to understand the trade-offs. The same room can lead to a different result after adding an opposite cabinet run or changing the target at one end.

Choose a clearance for each use

The initial 120 cm target is an editable example from IKEA’s ENHET planning guide. It is about 47.2 inches, not 48 inches. Our guide to space around an island distinguishes work aisles, walkways and seating references, with links to the original sources.

A maximum-size result uses all the allowance you selected. You may prefer a smaller island to leave more room for passing, doors or changing how you use the kitchen. Compare the arrangement with an L-shaped kitchen or peninsula before reducing every gap to force an island in.

What this plan includes

The model supports a rectangular room, a rectangular island and up to four full-wall cabinet bands. It uses the outer worktop footprint, including overhang. A short cabinet run is represented conservatively as a full strip; the tool does not recover the free space beside its end.

It does not model irregular walls, door or drawer swings, seating occupancy, windows, plumbing, electrical work, fixing or ventilation. It does not assess accessibility or local installation requirements. Use a measured plan and actual appliance specifications for those decisions.

Common questions

Why is the maximum size not always a useful island size?

The result fills the remaining rectangle. A very narrow footprint may not accommodate cabinets, and a very deep one may be difficult to reach across. Your intended use and the actual products determine whether that footprint is useful.

What if no island fits?

Zero or a negative available dimension means the chosen bands and gaps use that axis completely. Check the inputs, then compare a different layout. The tool will not silently reduce your clearance targets.

Where is my saved plan stored?

Save here stores one plan in this browser on this device. Share plan puts the measurements in a link that someone else can open. Neither action needs an account. Print plan uses your browser’s print or PDF option.

Does a green result mean I can install it?

It means the geometric gaps meet the targets you entered. It does not confirm appliance operation, seating, fixing or compliance. Check those separately with your designer or installer.

Method and examples by the BTTR Space editorial team. Reviewed against the stated geometry on 21 September 2026. Editorial approach.