Built-in ovens: How we test built-in ovens

Which? tests many of the bestselling ovens from all the major brands and we also look for the latest launches or interesting models, particularly if they have innovative features or a ground-breaking design. We test gas and electric, single and double, as well as built-in and built-under models. Those that score particularly well get the accolade of Best Buy built-in ovens.

Video guide: what makes a Best Buy built-in oven

Check out our video to see why a Best Buy built-in oven will make a real difference to you.


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Practical oven capacity test

A fake turkey in an oven

We use large fake turkeys to test how much you can actually fit inside each oven

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.

Usable oven capacity tests

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 from the top of the oven. We don’t include the space beneath the lowest shelf.

Oven heat distribution test

Baked strips of shortbread

Baking shortbread shows how well oven heat spreads

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.

Oven baking test

In each oven we bake a large sponge cake and measure how well and evenly the cake rises. We also record how evenly the cake is browned.

Oven pre-heating speed and accuracy test

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

We also record how accurately they heat – Best Buys get very close to the set temperatures, but the least accurate ovens can overheat by more than 40°C.

Grill test

25 slices of toasted bread

Good grills will spread heat evenly across the grill pan

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

Oven energy tests

We simulate roasting a whole chicken by heating 2kg of bricks in the main oven for 1hr 40 mins. Electric conventional ovens are set to 200ºC, electric fan ovens are set to 170ºC and gas ovens at gas mark 6. We record the amount of energy each oven uses while cooking, and we turn this into a score based on the running costs for each model.

Which? oven testing methods

Some ovens in our online review have a note showing that they were tested before 2011. Since then we’ve changed the way we test ovens, and although you can generally compare older results with the latest oven test results, they don’t directly correspond. However, each score still gives a very good indication of the overall performance of the oven.

When awarding a score to an oven we primarily look at how well it cooks food, both with regard to the oven and the grill (oven performance is more heavily weighted). We also take into account ease of use, ease of cleaning, and energy efficiency. The score breakdown looks like this:

  • Performance................. 60%
  • Energy efficiency......... 10%
  • Ease of use................... 20%
  • Ease of cleaning........... 10%

Best Buy models need to score 76% or above.

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