An air fryer is a small convection oven. That is not a criticism — it is the whole explanation of what it does well, what it does badly, and whether you need one alongside the oven you already have.
What is actually different
A conventional oven heats a large cavity and moves air gently, if at all. An air fryer heats a small cavity and moves air through it fast. Three things follow:
- It preheats in two to three minutes instead of ten to fifteen, because there is far less air and metal to bring up to temperature.
- It browns faster at the same set temperature, because moving air carries heat to the food's surface more quickly than still air.
- It holds much less. The basket that suits two portions will not do a tray for six.
A fan oven sits between the two. If your oven has a fan setting, you already own a slower, larger version of the same technology.
Where the air fryer genuinely wins
Small quantities. Heating a 60-litre oven to cook a handful of chips is wasteful in both time and energy. The saving is real and it is mostly about volume, not efficiency.
Reheating anything that should be crisp. Leftover roast potatoes, pastry, breaded food and pizza come back far better than in a microwave, and faster than in an oven.
Food that benefits from dry, fast air. Frozen chips, chicken wings, halloumi, tofu, roasted chickpeas and most breaded things. Anything where you want the outside dry before the inside overcooks.
Where the oven still wins
Volume. A single tray of vegetables for a family will need two or three batches in most air fryers, which erases the time saving.
Anything with a wet batter. Fast-moving air blows thin batter off food before it sets. Breadcrumbs work; a tempura-style batter does not.
Baking that needs even, gentle heat. Cakes, custards and bread generally do better in still or slow-moving air. Some air fryers bake acceptably; very few bake well.
Large or oddly shaped things. A whole chicken fits in some models, but the basket geometry usually forces you to turn it mid-cook.
Reading the capacity figure
Air fryer capacity is quoted in litres and it is misleading. A "5.5 litre" basket does not hold 5.5 litres of food, because air fryers only work when air can circulate. The usable amount is roughly half the stated volume for anything that needs to crisp.
A more useful question than litres is the surface area of the basket floor. Crisping happens in a single layer. Two baskets of the same litre rating can differ substantially in how much food they can cook in one layer, and the wider, shallower one wins.
Energy, honestly
An air fryer uses less energy than an oven for a small load, because it heats less space for less time. For a full oven's worth of food, the oven is usually the more efficient choice — you would be running the air fryer three times.
The saving is meaningful for the way many people cook on a weeknight and negligible for a Sunday roast. It is worth having the expectation the right way round.
Do you need both?
If you cook for one or two, reheat often, and rarely fill an oven shelf, an air fryer will get used far more than you expect and the oven far less.
If you cook for four or more, or bake regularly, an air fryer is a useful second appliance rather than a replacement — good for the crisp things and the reheating, still second to the oven for the main event.
If your oven has a fan and you are trying to decide between them, the honest answer is that the air fryer buys you speed and the oven buys you space.
More kitchen notes are filed under Home & Kitchen.