How we test built-in ovens

How we test built-in ovens

by Jane Darling

A built-in oven needs to be quick to heat up, stick to the correct temperature and bake food evenly for it to become a Which? Best Buy. 

If you choose one of our Best Buy ovens, you can be sure that you'll be getting a great model you can rely on to cook your food beautifully, whether it be a roast dinner or perfect cakes. Watch our video to see why a Best Buy built-in oven will make a real difference to you.

We rigorously test a range of big-brand built-in ovens, including single ovens and double ovens, both gas and electric. Our reviews answer your key questions about built-in ovens:

  • How much will I be able to fit in the oven?
  • How quickly will the oven heat up?
  • Will it accurately remain at the temperature on the dial?
  • Will the heat spread evenly throughout the oven?
  • How well will it grill my food?
  • How easy is it to use and how much will it cost to run?
  • Should I buy it?

Go straight to our built-in oven reviews to discover the best and the worst models. If you want to find out more about our testing, read on.

How much will I be able to fit in the oven?

The actual usable capacity of your oven can be different from what the manufacturer claims. So we use large fake turkeys, chickens and roast beef joints on roasting trays, along with another tray of roast potatoes, to find out what you can actually fit inside your oven. For double ovens we test both the main and top ovens.

We only measure the space that you will actually be able to use inside an oven. We measure the internal width from side to side, and the depth from the inside of the door to the back of the oven. But we only measure the height from the top of the lowest shelf to 3cm below the top of the oven. We don’t include the space beneath the lowest shelf, which manufacturers often do.

How quickly will the oven heat up?

We set each oven to heat to high and low temperatures, and we record how long they take to reach these targets. Heat settings for conventional electric and gas ovens are 180°C (gas mark 4) and 200°C (gas mark 6). For fan-assisted electric ovens, the settings are 150°C and 180°C. 

The best ovens take less than four minutes to heat up to 180°C, while the poorest ones will keep you waiting for nearly three times as long.

Will it accurately remain at the temperature on the dial?

We record how accurately an oven sticks to the temperature it says it's at. Best Buys stay very close to the set temperatures, but the least accurate ovens can overheat by more than 30°C. This is enough to result in burnt food

Will the heat spread evenly throughout the oven?

We use baking trays covered with 10mm-wide strips of shortbread to reveal just how effective ovens are at spreading heat right around the oven. The colour of the shortbread after cooking shows how evenly the oven distributes heat across each oven tray. The best ovens we’ve tested deliver heat evenly across the shortbread, but the worst leave some areas unbrowned and other parts burnt.

We bake a large sponge cake in each oven and measure how well and evenly the cake rises, and how evenly the cake is browned.

How well will the oven grill my food?

We cover each grill pan in white crustless bread to see how well, how far and how evenly the heat spreads. The best grills we’ve tested can effectively heat more than 90% of the grill pan. 

The worst will struggle to heat anything more than the area directly beneath the element, or around 40%.

How easy is it to use and how much will it cost to run?

We use an independent panel to assess how easy each oven is to use, including looking at how straightforward it is to set the ovens and grills, how clear the markings are and how easy it is to check up on food while it is cooking.

To see how much the oven will cost to run, we test each model's energy efficiency by simulating roasting a whole chicken, which we do by heating 2kg of bricks in the main oven for 1hr 40 mins. Electric conventional ovens are set to 200ºC, electric fan ovens to 170ºC, and gas ovens at gas mark 6. We record the amount of energy each oven uses while cooking, and we convert this into a score, based on the running costs for each model.

76%The score a built-in oven needs to earn to be a Which? Best Buy

Should I buy it?

When awarding a score to an oven, we place greater emphasis on its crucial functions: how well it cooks food, both in the oven and the grill (oven performance is more heavily weighted). However, we know that ease of use, ease of cleaning and energy efficiency are also important to you, so we take these into account, too.

The complete score breakdown looks like this:

  • 60% performance
  • 20% ease of use
  • 10% energy efficiency
  • 10% ease of cleaning

In order to become a Best Buy, an oven needs to score 76% or above. If an oven does poorly and scores less than 40%, we suggest you steer clear of it and we highlight it as a Don't Buy.

Go straight to all our Best Buy built in ovens.