By moving fast hot air past the food, convection ovens can operate at a lower temperature than a standard conventional oven and yet cook food more quickly. The air circulation, or convection, tends to eliminate "hot spots" and thus food may bake more evenly. A convection oven will have about a 50 degree Fahrenheit (30 degree Celsius) reduction in cooking temperature, compared to a conventional oven. This comparison will vary, depending on factors including, for example, how much food is being cooked at once or if airflow is being restricted by using an over sized baking tray).
Many convection ovens also include a proofing capability using the same fan but at a much lower temperature. A residential double oven will often include the fan capability in only one of the two ovens.
Another form of a convection oven is the commercial impingement oven. This type of oven is often used to cook pizzas in restaurants. Impingement ovens have a high flow rate of hot air from both above and below the food. The air flow is directed onto food which usually passes through the oven on a conveyor belt. Air flow rates can range between 1-5 m³/s. Impingement ovens can achieve a much higher heat transfer than a conventional oven.
Like the "impingement oven" a convection oven usually has the radiant elements in view of the food, which improves heat transfer and speeds cooking from initial cold start. Some ovens have the heating elements placed in an outside enclosure and hidden from the food. This eliminates radiant heat from direct contact with the food.