How to choose a microwave

Getting started

Make a list of what you need your microwave to do.

Sophisticated combination microwaves have many programmes and functions, but aren't worth your money if you just want the convenience of heating up a mug of soup or a ready-meal when you're in a hurry. Top-range models can be used for grilling and baking, and some even have a yogurt-making function. If you batch cook and store a lot of frozen food, a good defrosting programme will be important. Think about where the microwave will sit. Bear in mind that it needs a gap of 15cm above and behind it for ventilation. This is particularly important for a combination oven, because a lot of air is expelled when using the dual function. Microwave ovens can be hung on the wall using special brackets to save space. If a microwave is built-in to a kitchen, you will need a ventilation kit, available from the manufacturer. When you're comparing models, the turntable size and interior height are more important than volume. For family use, ideally the turntable diameter should be at least 30cm and the interior height more than 20cm to accommodate larger portions of food.

The options

Microwave only

Often referred to as solo microwaves, this basic option is ideal for simple tasks such as cooking ready-meals, reheating and defrosting, but it won't crisp or brown food. Approximate size for a solo is H27 x W44 x D34cm.

Microwave with grill

You'll get all the regular features of a microwave, but with an internal grill. By using a heating element together with normal microwave cooking, your food will be browned as well as cooked, giving it a more attractive appearance and texture - you can even cook a roast chicken. Bear in mind, however, that the grill element is likely to be less powerful than a conventional grill, so toasting may be slower and foods can become drier. Models come with a metal rack for grilling, and both the grill and microwave can be used separately. Sizes are much the same as solo models at H27 x W45 x D34cm.


Combination microwave ovens offer more flexibility when cooking and allow you to use microwave only, grill only or convection (hot air) heat only. You can also use the microwave and grill together. The best combination microwaves can produce excellent baking results. Some models even offer a steaming function. Sizes for these models are bigger at around H35 x W52 x D50cm.


A great way to free up workspace, built-in models are available in every style from microwave only to top-of-the-range combinations. Built-in models are approximately H46 x W60 x D55cm.


This varies from about 17L to over 32L. For larger families, look for at least 27L, which will have a larger turntable and more interior height to cook more than one dish at a time.


Microwave power is measured in watts. The higher the wattage, the quicker your food will cook. Wattages range from between 650-1950W, and are categorised by a rating of A to E - at 850W, E is the most common rating. Microwavable food will clearly display both the appropriate category and power levels under the cooking instructions.


Essentially, microwaves cook by producing electromagnetic waves that force polarized water molecules within the food to oscillate.

We experience this atomic-scale movement as increasing temperature. Imagine water molecules as antennae, interacting with the waves in the oven much like a radio antenna does with radio waves.

The more water in the food, the more effective it is as an antenna. Plant foods have a high water content relative to most foods—making them very effective antennae indeed.

But it’s important, too, to consider the size of your antennae. In conventional ovens, small foods cook faster than larger ones.

It tends to be the opposite with microwaves. A microwave (that is, the wave itself, not the oven) is 12.8 centimeters long. To receive the waves properly, food should be at least a quarter of that length—so about 3.2 centimeters (a little larger than one inch).

Think about how an individual popcorn kernel can take minutes to pop. And yet, you can pop an entire bag of popcorn kernels in about 60 seconds. Grouped together, all the kernels form a target mass that can couple with the microwaves and absorb them in a manner similar to the way a radio antenna picks up radio waves. The lone kernels are so small (relative to the length of the microwaves) that they can’t easily absorb the waves’ energy, and therefore, they take longer to cook.

From an engineering perspective, the microwave oven is a fairly simple machine except for one complex and fascinating piece: the magnetron.

See the diagram below to better understand how energy flows from the socket in your kitchen into the food itself.

What does the stirrer blade in a microwave do?

The stirrer blades distribute the microwave energy to promote even cooking inside the microwave cavity. They prevent hot spots.

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