How we test cookers
What makes a Best Buy cooker?
The top-scoring models in Which? tests earn our Best Buy accolade. Our test lab reviews tell you which cookers have ovens that heat up quickly to the correct temperature and stay there.
They also reveal those with grills that make great toast, and hobs that rapidly heat your food or simmer gently. Watch the video above to discover more about what a cooker needs to do to become a Best Buy, and why choosing one of these will boost your cooking skills and enjoyment.
Our detailed reviews of cookers answer the most important questions for you, including:
- Will the oven in the cooker heat up quickly and spread heat evenly?
- How much can you fit into each cooker's oven?
- How evenly does the cooker's grill brown food?
- How effective is the cooker's hob?
- Is the cooker easy to use and energy efficient?
- Should I buy it?
Does the oven heat up quickly and spread heat evenly?
Everyone varies the temperature at which they use their oven, so our tests check how quickly the oven in each cooker reaches two set temperatures.
We set conventional electric ovens and gas ovens to heat up to 180°C (gas mark 4) and 200°C (gas mark 6), and fan-assisted electric ovens to 150°C and 180°C. As well as noting the speed at which they reach these temperatures from cold, we then record how closely each oven sticks to the set temperature. Our tests have found ovens that veer wildly away from what you would expect – sometimes by more than 40°C. Top-scoring , however, stick closely to the expected temperature.
Next, we bake a tray of shortbread in the oven. This delicate bake clearly shows how effective the cooker is at spreading heat evenly throughout the oven cavity. Ovens that leave pale parts or burnt corners get marked down in our tests, while those that turn the shortbread an even golden brown across the whole tray get top marks. See the picture below to see the kind of results ovens produce in our lab tests.
Our second baking test involves making a large sponge cake and measuring its vital statistics when it emerges from the oven. If it's well risen and evenly browned, it gets a high score, but flat, sunken or unevenly baked cakes lose points. Below is an example of a well-risen sponge baked in the oven of a Best Buy cooker.
How much can you fit into each cooker's oven?
Manufacturers give the total internal dimensions of an oven, but this doesn't give a clear picture of what you will actually be able to fit in. So we use a plastic turkey, chicken or roast beef joint and put it on roasting tray – then we add another tray if we can – to find out whether you'll get a full Christmas dinner in there, or if you'll be limited to a smaller Sunday roast. If the freestanding cooker has more than one oven, we try out both.
As well as using the fake roast joints, we also record the useable space within each oven. We measure from side to side, and the distance from the inside of the door to the back of the oven. When it comes to the height, we measure from the top of the lowest shelf to 3cm below the top of the oven, to give a real feel for the actual height available.
How evenly does the cooker's grill brown food?
We cut the crusts off white bread and cover the cooker's grill pan with it, to let us see how far and how evenly the grill spreads its heat. A great grill can brown virtually all of the bread, but our tests have found many that struggle to heat more than 50% of the area – and the worst models only toast bread that is placed directly under the element. This means that you would find yourself shifting food around to get anything approaching even browning.
How effective is the cooker's hob?
When you're in a hurry to heat your soup, a freestanding cooker with a speedy hob will do the job. We test how rapidly each hob will heat up a panful of water from 15°C to 90°C. Quick hobs take less than five minutes, but the slowest will keep you waiting more than double this time. Best Buy hobs also excel at the other end of the scale, allowing you to simmer delicate ingredients.
If you regularly fry bacon, then you'll be interested in our heat-distribution test, where we measure how well heat spreads across the base of a frying pan – the best hobs spread the heat evenly rather than concentrating it in particular spots. Our final tests involves recording what happens when you power down the hob – some retain heat and will keep cooking your food, while others cool down quickly.
Is the cooker easy to use and energy efficient?
An independent panel judges each freestanding cooker for ease of use. They look at how easy it is to use the settings on the ovens, grills and hob, as well as how clear the markings are and whether you have a clear view into the oven while food is cooking.
As all food is variable, we maintain consistency by heating up 2kg of bricks in the main oven for 1hr 40 mins. This simulates about how long you'd roast a whole chicken for. In freestanding cookers the conventional electric ovens are set at 200°C, electric fan ovens to 170°C and gas ovens to gas mark 6. We measure how much energy each oven uses, and convert this into a score based on the running costs for each model.
Should I buy it?
You've told us that the most important features of a freestanding cooker are the oven, grill and hob, so we put more emphasis on these areas of our tests when we award a cooker an overall score.
On top of this, we know that how easy the cooker is to use and clean are both considerations, along with how efficient the cooker is.
The full score breakdown is as follows:
- 40% oven performance
- 25% ease of use, including ease of cleaning
- 20% hob performance
- 10% grill performance
- 5% energy use
Freestanding cookers need to score 68% overall in our tests to be a Best Buy. We think that any cooker that scores less than 45% is best avoided, so we highlight it as a Don't Buy.