Should you use the fan setting on your oven?

Most ovens sold today have a little fan symbol among their settings, and most recipes give two temperatures, one marked "fan". It is worth understanding what that fan does, because it changes how heat reaches your food, not just how hot the oven is.

What the fan changes

Wikipedia's entry on convection ovens (fan ovens, in British kitchens) explains that a fan circulates hot air around the food to create an evenly heated space. Without a fan, natural convection moves the air unevenly, so a conventional oven tends to be cooler at the bottom and hotter at the top than in the middle.

The same entry describes why fan ovens cook faster: food sitting in still air is wrapped in a thin layer of cooler air that slows the heat getting in. The moving air of a fan thins that layer, so heat transfers more quickly. To avoid overcooking the outside before the middle is done, it says, the temperature is usually set about 20°C lower than for a non-fan oven.

In practice:

• Things brown and crisp faster.
• The whole oven is more even, so you can use several shelves at once.
• Surfaces dry out more, which is great for crisp skins and edges, less great for some cakes and custards.

Adjusting temperatures

• If a recipe gives a fan temperature, use it.
• If it gives only a conventional temperature, reduce it by about 20°C for fan, as a starting point.
• Check earlier than the recipe suggests. Every oven is different, and fan ovens often finish sooner.
• An oven thermometer is a cheap way to discover how your oven really behaves.

Your oven's own manual is worth a read too; manufacturers sometimes have particular advice for their settings.

When the fan is the better choice

• Roasting vegetables and potatoes. The circulating air drives off moisture and gives better browning. Our pages on soggy roast vegetables and crispy roast potatoes go further.
• Baking on several shelves. Biscuits, trays of vegetables or several pizzas at once cook more evenly.
• Crisping and reheating. Breadcrumb toppings, gratins, croutons and leftover pizza all perk up.
• Toasting nuts and seeds, evenly and quickly (keep an eye on them).

When to switch the fan off

• Delicate cakes and sponges. Moving air can set the outside before the cake has finished rising, giving a domed or cracked top. Many bakers prefer conventional heat for these; if you use fan, lower the temperature and keep an eye on it.
• Custards and creamy bakes, which can skin over or set unevenly.
• Bread and pizza needing strong heat from below. A conventional setting with bottom heat, or bottom heat plus a preheated stone or steel, helps the base cook. Our page on pizza in a home oven explains.
• Very light things that blow around, like a loose crumble topping or baking paper not weighted down.
• Slow braises in a covered pot, where the fan makes little difference; either setting works.

Other settings worth knowing

Many ovens also offer:

• Conventional (top and bottom heat): the classic, still air setting most old recipes assume.
• Grill: strong heat from the top, for browning a gratin or melting cheese.
• Fan with grill or bottom heat: combinations useful for pizzas, pies and crisping.

The names and symbols vary by brand, so check the manual for what yours does.