How long to pre-heat the oven

Just about every baking recipe that I read has the instruction of baking the dish for a specified time in an oven preheated to a certain temperature. In this era when we are all trying to do our bit to cut unnecessary energy use, I find myself asking How long to pre-heat the oven to get it right. Maybe I’m switching my oven on too soon and wasting energy.

Most ovens take between 10-15 minutes to preheat to standard baking temperature. Factors such as low wattage, colder room temperature, and constantly opening the oven to check the temperature can slow the process of preheating.

Pre-heat oven

Let’s take a look at how long it takes for those cookies to go in the oven and the factors that affect how quickly an oven preheats.

How Long Should The Oven Be Pre-heated

When it comes to cooking food in the oven most ovens take between 10-15 minutes to heat up to the right temperature. There are some older model ovens that don’t have temperature settings but rather just an on/off switch.

If you have one of these, all you need to do is switch the oven on and wait for the same 10 to 15 minutes so that the oven can come to temperature.

If you intend to be baking in your oven, it will need to preheat to a higher temperature. This means that you will need to wait for 20 to 30 minutes before popping your cake or bread into the oven. 

The extra time will help ensure that your baking is cooking evenly all the way through and give you perfect results.

How Do You Know When The Oven Is Ready

Most modern ovens have an alarm that sounds once the oven has preheated to the correct temperature. Other newer ovens have a display that shows the temperature reading of the oven so that you can see how close the oven is to the optimum temperature that you want. 

In many instances, the ovens that have a temperature display will also have an alarm that sounds once the oven is at the correct temperature.

It is feasible that the feature that your oven has for showing you that it has reached temperature could become faulty, so it is useful to keep a separate timer going so that you can see how many minutes of preheating time you have left.


Remember that some modern ovens take longer to preheat than older models. This happens because the heating elements are hidden behind the walls of the oven as opposed to the exposed elements in older ovens. 

This has been done to make the cleaning of the oven easier as the elements won’t be covered in food splatter.

When I was a child, learning to cook, my mother’s electric oven had neither a temperature display nor an alarm. Her stove had two red lights under the dial to turn on the oven and set the temperature. 

When I switched on the oven, both lights came on. When the oven had finished preheating the left of the two lights went out. No instructions whatsoever lol. It was all the same for roasting, bake time, pot roast,…no pilot light on sight! 

How to know if your oven is preheating to the right temperature?

The correct way to check if your oven is preheating to the correct temperature is by hanging an oven thermometer in the center of your oven, just above the center rack. Set the oven temperature to 350F (176.67C) and allow the oven to preheat for at least 20 minutes before taking a temperature reading.

From this single reading, you can confidently tell whether all of your oven’s temperature settings are accurate or not.


I must admit that I have never owned an oven thermometer, much less thought of checking to see how accurate the temperature of my oven is. I contacted my old school friend Bjorn about this. He studied hotel management in Zurich and trained as an assistant chef under a Michelin Star chef in London. He told me that all of the ovens in his hotel are checked for temperature accuracy every 60 days, something he learned to do during his chef training.

Is It Bad To Put Food In The Oven Before It’s Preheated

All of the recipes that I have seen indicate that I should place my dish in a preheated oven. Never have I seen anything about putting a dish into a cold oven.

I thought that perhaps cooling food at a lower temperature will prevent the food from cooking all the way through and create the possibility of food poisoning from undercooked food. 

Here again, my friend Bjorn, the hotel manager/chef, reassured me that it is very unlikely that any dish placed into a still heating oven and cooked for two hours or longer will fail to make it to a safe temperature.

Croissants in oven

He did say that soufflés, egg dishes, and meringues need a preheated oven otherwise they will fall flat before they are even properly cooked.

Putting bread into a cold oven can make the bread dense, dry, and crumbly. My neighbor, Gerardo, owns a small family-run bakery in our village and he gave me a useful hack on how he bakes his bread every morning. 

One of the bread varieties that he does is the thick-crusty, rustic, artisan loaf. He creates the thicker crunchy crust by placing the loaves into the oven midway through the preheating process and then baking the bread for the normal amount of time from when the oven is up to full temperature.

Pizza, for example, has to go in the oven at very high temperature and the oven needs to be really, really pre-heated.

Factors Affecting The Preheat Time Of An Oven

There are a number of variables and external factors that can impact how long it will take your oven to preheat.

The Wattage Of The Oven

An oven will be rated with a higher wattage because it either has more heating elements or the heating elements can draw more power and get hotter. As a result, a higher wattage oven will preheat faster and a lower wattage oven will preheat slower.

higher wattage oven

Room Temperature

It may not seem obvious at first, but the colder the temperature in your kitchen, the longer it will take to preheat your oven. For instance, your oven will take longer to preheat in winter when the temperatures are colder.

This factor applies more to domestic kitchens than commercial kitchens where restaurant chefs are usually cooking on multiple gas hobs and deep fryers meaning that the temperature in a restaurant kitchen stays high, even in winter.

Opening The Oven’s Door During Operation

Every time you open the oven door during the preheating process so that you can check the temperature and how well your oven is preheating, you are allowing the hot air from inside the oven to escape and therefore heat loss occurs.

This slows down the process of preheating, especially if you do this repeatedly during the preheating process.

Cooking pizza

Production Year And Model Of The Oven

The make, model, and production year of your oven can impact the preheating speed of your oven.

Some newer model ovens are higher wattage units and therefore preheat more quickly. 

Conversely, other newer models of ovens have heating elements that are hidden behind the walls of the oven to make cleaning easier. However, non-exposed heating elements equate to a slower preheating process.

How To Prepare An Oven For More Efficient Preheating

In order for your oven to preheat more efficiently, there are a few things that you can do before you switch your oven on.

Clean The Oven Before Using It

Make sure that the oven is clean. Pay particular attention to any baking or drip trays that might still be in the oven from the last time you did bake something.

This can negatively impact how quickly your oven preheats. Also, the smoke from a dirty drip tray/baking sheet could spoil the taste of whatever you are currently cooking in the oven.

Cleaning your oven

Rearrange The Oven’s Racks To Where You Want Them

Before switching on your oven, rearrange the oven racks to where you need them to be. Firstly, because you don’t want to open and close the oven unnecessarily. Secondly, it is much easier to rearrange your oven racks when they are cold.

Ensure Proper Ventilation In The Room

This last point is vital when you are using a gas oven at any time. However, it is also important when using an electric oven, especially in summer when the inside of your kitchen can become unpleasantly hot when you are doing a lot of baking.

Can I put my food in the oven while it’s preheating?

While it’s generally not recommended to put most foods in the oven before it reaches the right temperature, there are some exceptions. Casseroles, which often consist of ingredients that are not highly sensitive to slight temperature variations or lasagna may be an exception. 

However, there are still some important considerations to keep in mind:

Cooking time adjustments:

If you decide to place a casserole in the oven, you should be prepared to adjust the cooking time. Since the casserole will begin cooking at a lower initial temperature, it may take longer to cook through. Keep a close eye on it and check for doneness by using a food thermometer or by visually inspecting the dish.

Quality and texture: 

Placing a casserole in a preheating oven could potentially affect the texture and quality of the dish, as it may cook unevenly at the beginning.

Safety precautions: 

Be cautious when using this method, especially if the casserole contains ingredients like raw meat or eggs, as they may pose food safety risks if not cooked properly.

In general, it’s still best practice to preheat your oven to the recommended temperature before placing your food inside. Preheating ensures consistent cooking results and minimizes the risk of undercooking or uneven cooking. If you are in a rush, you can consider using a convection oven, which often has a shorter preheat time, or other cooking appliances like a microwave or stovetop to partially cook or heat ingredients before transferring them to the oven.

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