It's tempting to buy one liner for everything, but the shape of your basket changes how well a liner works.
Why shape matters
A liner that matches your basket sits flat with its walls against the sides. That means more usable cooking area, better airflow around the food, and no loose corners flapping toward the element.
Round in a square basket
A round liner in a square basket leaves the corners uncovered — grease gets through and you lose space. Fine in a pinch, not ideal.
One-size in a slim basket
Ninja and Bella slim baskets are long and narrow. Only a rectangle liner covers the full base; a round one wastes both ends.
The simple rule
Buy the shape that matches your basket: square for square, round for round, rectangle for slim, and mini for compact fryers. Everything else takes care of itself.
