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What is an inverter microwave?

How does an inverter microwave differ from a normal microwave and are they worth considering?

A person using an inverter microwave at home
Last updated: 18 June 2021
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Need to know

  • The difference between inverter and normal microwaves is in the way power is delivered
  • Inverter microwaves provide a constant stream of power for the entire cooking time to avoid overheating
  • Understanding the importance of power levels and how to use a microwave properly will go a long way towards getting great results

Microwaves tend to be a staple item in any kitchen – you can use them to reheat leftovers, defrost meat or cook veggies and rice. When it comes to shopping for one, there are normal conventional microwaves and then there are inverter microwaves that claim superior performance. 

But what's the difference between the two and do inverter microwaves actually perform better? We've put many microwaves to the test in our labs, with and without inverter technology, to find out.

How does an inverter microwave work?

An inverter microwave works by heating, reheating or defrosting food at a constant power level for the duration of the cooking time. 

The aim of inverter technology is to provide a controlled and efficient power supply operating continuously at the same power to avoid overheating, loss of flavour and destroying food structure.

What is the difference between an inverter and a normal microwave?

The main difference between inverter and conventional microwaves is in the way power is supplied. In a conventional microwave power is supplied through a transformer, which turns the power on and off (you'll usually hear the microwave cutting in and out), giving the food a chance to distribute heat. 

For example, if you set the microwave to deliver 50% power, it will actually go through cycles of producing 100% power followed by a period of no power to achieve the 50%.

On the other hand, in an inverter microwave power is supplied through an inverter circuit to supply a steady and constant amount of power throughout the cooking time without cutting in and out. So if you select 50% power, the microwave will deliver 50% power throughout.

Not all foods should be blasted with maximum power in a microwave. Foods with high amounts of sugar and fat, as well as foods sensitive to heat like dairy, chocolate and meat (when defrosting) require lower power levels to effectively heat and reheat evenly. 

Even if you're using a lower power level, heating delicate foods in a standard microwave can cause areas to overheat (especially around the edges) during periods of high power. Checking the manufacturer's instructions and recommendations will go a long way towards getting power levels right for different foods.

Melting chocolate test

In our latest test of microwaves we put this to the test by melting chocolate – a very heat sensitive, high fat, high sugar food. All the inverter models in the test had a melt/soften function, as did one of the non-inverter models. 

In this case, all the inverter microwaves passed the test, melting the chocolate perfectly. One inverter model was able to do the job with no user interaction whatsoever. The other inverters all beeped part way through to prompt the user to check and stir. 

The normal microwave failed the test – it didn't beep to prompt checking and stirring and the result was unusable chocolate. In this case the inverter (teamed with auto cook functionality) microwaves performed better than the conventional microwave.

Infographic showing the difference between inverter and conventional microwaves

Infographic: Inverter microwaves provide a constant stream of power for the entire cooking time to avoid overheating.

What is the benefit of an inverter microwave?

There are many claims regarding the superiority of inverter technology, all of which generally praise the steady stream of power delivery. 

Panasonic says that inverter technology "delivers a seamless stream of cooking power – even at lower settings – for precision cooking that preserves the flavour and texture of your favourite foods". 

According to LG, "Inverter technology enables more precise temperature control to help defrost foods and avoid overcooked and unthawed areas." 

Some of the top performing models in our microwaves review have inverter technology, however, there are some recommended conventional microwaves that perform just as well. We believe there are more factors to consider when choosing a microwave than just inverter functionality.

The importance of power levels when using a microwave

We've all done the old trick of pressing the Start 'Add 30 seconds' button on our microwaves, thinking that pressing the button a couple of times is the quickest way to reheat a meal. While this may be the case, it actually doesn't leave you with a great result. 

When you reheat meals this way your microwave is using its highest power level for the duration of the time selected. This results in areas of the meal that are very hot and areas that are still cold and the need for you to manually stir or mix the food to achieve even heating. 

By blasting the food with maximum power it's not giving the microwave a chance to distribute heat evenly. This is especially true for solid foods like lasagna where you can't stir the food during reheating. 

Instead, it's best to use a lower power level (if sensor reheat isn't available). It may take longer to reheat but you'll get a better result. 

It's a similar story when defrosting meat. The power level is particularly important when defrosting – too high power will result in uneven thawing, with areas becoming warm or cooked and others staying frozen. The microwave should only be operating at around 30% power for defrosting. If your microwave has a defrost function, use it.

Is an inverter microwave worth it?

In theory, the way inverter microwaves work should mean they always perform better. But in our testing, this isn't always the case and we believe there are other factors that make a good microwave. 

You should look for a microwave with well-designed sensors, autocook functions and good visibility as well as ease of use rather than just inverter functionality. 

We find that most of the inverter microwaves we've tested also have sensor cook functionality and generally the combination of these two features works well in our testing. The inverter microwaves we've tested range in price from $227 to $419.

Microwaves are a tricky appliance to navigate and understand how to use properly, especially in terms of power and how to adjust it correctly. Based on this we'd suggest looking for a microwave that requires minimal interaction from the user and a well-designed inverter or sensor microwave is an option worth considering.

Which brands offer inverter microwaves?

In our kitchen lab we've tested inverter microwaves from:

  • Breville
  • LG
  • Morphy Richards
  • Panasonic
  • Sharp

You can also find inverter microwaves from other brands like Bosch and Smeg.

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