What Your Oven Is Actually Doing

Set it to 200C and it is not at 200C

A domestic oven cycles its element on and off around the set point, so the real temperature is always moving — and the average is commonly 20-30C away from the dial. It varies between ovens, and within one oven between the top and bottom.

An oven thermometer settles this permanently. They cost very little, and one measurement explains half of all "I followed the recipe and it did not work". If yours runs 20C cool, set it 20C higher and move on.

Preheating takes twenty minutes, not five

When the oven beeps, the only thing that is hot is the air. The walls, the floor, and any tray or stone inside are still cold.

A large share of baking heat is radiation from those surfaces, so food going into an air-only oven sets its crust late. Anything that needs strong early base heat — pretzels, pizza — shows it clearly.

Work on twenty minutes. Better still, preheat the tray inside it.

Opening the door costs 30C

Hot air leaves upward the moment the door opens, and refilling takes minutes. For anything mid-rise — soufflé, cake, croissants — that is decisive.

• Do not open during the first two thirds of the rise.
• Check through the glass with the light on.
• If you must rotate a tray, do it once and fast.

Convection means lowering the number

A fan strips away the thin boundary layer of still air at the food's surface, so heat transfers much faster. At the same dial setting it behaves like roughly 20C hotter.

• Converting a conventional recipe: drop 20C, or cut 20% off the time.
• Good for: several trays at once, anything whose skin should dry, roasted vegetables.
• Bad for: anything whose surface must not dry — custards, cheesecakes, delicate cakes. Something like Basque cheesecake, where you want the top scorched, suits it well.

Rack position matters as much as the recipe

• Middle: the default, top and bottom heat balanced.
• Low: when the base must cook — pies, pizza, the first stage of lasagna.
• High: when the surface must colour — the last ten minutes of moussaka or a gratin.

A large part of why one kitchen's results differ from another's is rack position, and most recipes never mention it.

The pan's colour is a temperature setting

• Dark, matte tins absorb radiant heat and brown the base fast. They also burn faster.
• Shiny, light tins reflect, so everything takes longer.
• Glass and ceramic heat slowly and hold heat afterwards.

Changing nothing but the tin can move a bake by ten minutes (browning and maillard).

An air fryer is not a fryer

An air fryer is a small convection oven with a strong fan. It does not fry; it dries the surface with fast hot air, which is a different result from oil.

Being small it preheats quickly and its airflow is fierce, so when converting an oven recipe start by dropping 20C and cutting 20-25% of the time. Something meant to be deep-fried, like a samosa, will come out layered but without the glassy shatter — lighter, and a different food (dry heat and moist heat).