How Much Energy Does a Microwave Use? | The Light Lab

How Much Energy Does a Microwave Use?

Saving energy (and money) is always easier when you know how much you’re using. But because many of the convenient smaller appliances we use seem to draw small amounts of power, we all too often discount how their use really does impact our electricity bills. With our How Much Energy Does This Appliance Use? series, we’ll examine what’s watt in small appliances to see approximately how much they use. To help you understand very basic electrical consumption calculations, you’ll need to keep a simple equation in mind: Volts (V) x Amperes (I) = Watts (W). What you’ll discover is how just how small appliances can contribute to your home’s energy usage and how these little conveniences can make big differences on your bill.

The microwave has become a must-have in modern kitchens mostly because of its convenience. The ability to “zap” leftovers in a matter of seconds or fully cook frozen meals in minutes makes it possible to enjoy hot food with minimum waiting and mess. But microwaves are also incredibly energy-efficient, and they offer savings potential that goes beyond the energy you put into your cooking.

How Much Energy Does a Microwave Use? | The Light Lab

How Much Electricity Does a Microwave Use While Cooking?

We’ll cut to the chase — unless your microwave is a massive model and you’re running it for several minutes at every mealtime, your energy cost amounts to a few cents per month, or a few dollars per year.

Exactly how much your microwave is costing you comes down to a few major factors:

  • What’s your microwave’s wattage? On the low end, tiny microwaves start at around 600 watts. Many full-size microwaves fall between 800 and 1,200 watts. Larger, commercial grade models may run 1,800 watts or higher. If you’re unsure of your microwave’s wattage, look for an attached label with that information, which may be inside the oven.
  • How often do you use your microwave? Microwaves use a small amount of standby power (which we’ll get to in a moment), but much of their energy goes into cooking. So the more often you cook, the higher your microwave bill.
  • What power settings do you use? If you’re always using your microwave at 100 percent power, it will consume close to its listed wattage whenever it’s in use. But most microwaves offer settings that allow you to use a fraction of the maximum power, as well as other low-power settings like “defrost” and “melt.” When you use these settings, your energy consumption is a little lower.

Imagine your microwave is rated for 1,000 watts, which is typical for a full-size countertop model, and your electricity rate is the national average of 12 cents per kilowatt hour (kWh). At full power, that microwave will consume about .02 kWh per minute, which will cost you about one fifth of one penny. If you used that microwave one minute every day for a year, it would cost you about 73 cents in cooking power. If your average was five minutes per day, that’s just $3.65 per year — still pocket change.

How Much Energy Does a Microwave Use? | The Light Lab

How Much Electricity Does a Microwave Use on Standby?

Savvy energy consumers know that their microwaves are always drawing some amount of power. That digital clock isn’t powering itself!

The exact amount of standby power varies by model, but usually comes in around five watts, give or take a watt or two. If you’re really curious about the standby power consumption of your microwave, the best way to pin it down is to use an electricity monitor that you can plug your microwave directly into.

Keep in mind that this standby power is flowing whenever the microwave is plugged in, and for most of us, that’s 24 hours a day. At 12 cents per kWh, a microwave that uses five watts of standby power will cost you about 44 cents per month, or $5.26 per year. That’s right — the cost to power the digital clock is higher than the cost of cooking in our example, if only by about a buck and a half per year.

If that seems wasteful to you, there’s no harm in leaving your microwave unplugged when it’s not in use. If you use a power strip to connect your microwave and other kitchen countertop appliances, you can easily cut the power to multiple standby power users at once, like your coffee maker and toaster oven.

Another Energy-Saving Microwave Perk

Compared to a full-size oven and range, microwave cooking is significantly more energy efficient. But this way of cooking has another benefit, especially in the summer — microwaves won’t heat up your home.

Air conditioning accounts for a far bigger slice of the energy consumption pie than all cooking-related energy put together. And when your cooking method introduces unwanted heat into your home — such as when you fire up your oven — that big slice gets even bigger. So relying on your microwave more during warm weather is a smart way to save on both cooking and comfort.

Most homeowners will spend just a few dollars per year powering their microwave ovens. So when it comes to cooking with your microwave, you have more to gain by counting calories than by pinching pennies.

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Josh Crank is a freelance writer with a background in legal journalism, travel writing and marketing. He's found his perfect fit in writing about home maintenance and repairs, energy efficiency, smart home technology and other topics to help readers make home life green and comfortable. Josh lives with his wife, two sons and endlessly howling beagle-basset hound mix in New Orleans.