A standard base corner holds about 0.4 cubic metres and gives you access to roughly half of it. In a kitchen with six base units, that is one whole cabinet you paid for and cannot reach. It is the single most wasted space in most kitchens.
Why it happens
Two runs meeting at ninety degrees create a void behind the door. A standard hinged corner door opens onto the front of that void and the back of it is out of arm’s reach, so it fills with the roasting tin you use at Christmas and a bag of carrier bags.
The options, worst to best
Plain hinged door
Cheapest and worst. Only worth it if the corner is genuinely for things you use twice a year, in which case be honest and treat it as deep storage rather than pretending otherwise.
Carousel or lazy susan
Rotating shelves. Better than nothing, but the circle inside a square leaves the four corners empty, so you still lose around a third of the volume. They also have a weight limit that people ignore and then wonder why it sticks.
Le Mans or magic corner pull-out
Shelves that swing out of the cabinet towards you. These give you genuine access to almost all of the space and they are the right answer in most small kitchens. They are not cheap, but in a room where you are short of storage this is where the money does the most work.
Blank the corner off
The option nobody suggests. Stop one run short, fill the corner with a false panel, and put an open shelf or a slim full-height unit in the returned space instead. You lose the void entirely and gain something you can actually use, and it usually costs less than a mechanism.
Diagonal corner cabinet
A single door set at forty-five degrees. Good for a sink or a display cabinet in a larger kitchen, wasteful in a small one because the diagonal eats worktop at the busiest point.
The corner above
Wall corners are easier. Either run one set of wall units into the corner and stop the other short, leaving a return of open shelving, or take the corner as a tall unit to the ceiling. Two wall cabinets meeting in a corner with doors that clash is a detail worth avoiding at the drawing stage, because it cannot be fixed afterwards.
A rule of thumb
If the kitchen has fewer than eight base units, spend on the corner mechanism. If it has more than eight, blank the corner and put the money into a larder instead. A larder beats a corner every time for the same money.