Air fryer sizes are given in litres, and the number on the box is hard to picture. A tiny one makes you cook in three rounds while the first batch goes cold. A huge one takes up the counter and heats a lot of empty space for a single portion. The right size depends on how many people you cook for and on how you like to cook.
Use the sizer below. It follows the rule-of-thumb capacities that a large UK retailer publishes in its buying guide, then adjusts for how you cook.
Who are you cooking for?
How do you cook?
Capacity is the volume of the basket, not the amount of food you can cook well. Air fryers work by blowing hot air around the food, so food needs space between pieces. Pile it in and the pieces steam instead of crisping. That is why a 4 litre basket is a comfortable fit for one portion of chips but not for a family dinner, even though both are "food in a basket".
Shape matters as much as litres. A tall, narrow basket suits a chicken breast or a stack of nuggets; a wide, shallow one suits a layer of vegetables. A whole chicken needs extra room around it so the air can circulate, so it is the one item that sends many people up a size.
A single drawer cooks one thing at a time. A dual-drawer (or "dual basket") model splits the capacity in two, so you can do a main in one and vegetables in the other at different temperatures, and sync them to finish together. The litres on the box are then the total of both drawers, which is why a 9 litre dual model has smaller baskets than a 9 litre single one would.
That makes dual models most useful from about 6 litres up, and a good fit for households of five or more. If you mostly cook one dish at a time, a single large basket is simpler to clean and easier to store.
Pick the size for the food you cook most nights, not the feast you cook twice a year. You can always cook a big meal in two rounds.
Not by itself. An air fryer is a way of cooking, and a larger one does not make food healthier or less healthy. It can make it easier to cook vegetables, fish or lean protein with a small amount of oil, which is the useful part for most beginners. Portion size still comes from your plate, not the basket: a full basket is not a single portion. If you are not sure how much food is one portion, our hand-portion guide helps.
If you have a medical condition, are pregnant or breastfeeding, have or had an eating disorder, or take medication, talk to a doctor or dietitian before changing how you eat. This guide is general information, not medical advice.
Capacity guidance is a retailer's rule of thumb rather than a scientific standard, and brands measure capacity in slightly different ways, so treat the ranges as a starting point.