Microwave ovens have been making our lives easier for decades. Thanks to this brilliant albeit accidental invention, reheating (and even cooking) meals can be conveniently achieved even by those with the tightest schedules. However, does this type of convenience come at a hidden cost?
The cost to run a microwave depends on the equipment’s wattage, operational time, and electricity tariff and can be determined by using two formulas: 1) Power consumed (kWh) = Rated Power (watt) X Operational Hours (hrs) and 2) Electricity cost = Power Consumption X Electricity Tariff.
There’s no arguing that microwave ovens are almost always worth the charges on your electricity bill. However, if you want to trace your consumption down to the kilowatt and cent, this article is for you.
What Is a Microwave Oven
A microwave oven is a common kitchen appliance used to reheat or cook food and warm beverages. This is accomplished through the use of microwaves, hence the name.
Microwaves are high-frequency electromagnetic waves similar to radio waves. In a microwave oven, these waves are produced by a device known as a magnetron.
The metal on the inside of a microwave oven then reflects the microwaves onto the food. The water molecules in the food react by vibrating and this vibration creates friction between the molecules which, in turn, produces heat.
Because this heat occurs directly within the food molecules, the reheating or cooking process is significantly sped up. This is the general premise of a microwave oven, and the reason why this invention is so valuable to our everyday lives.
Microwave Size and Electricity
Microwave ovens are available in a wide range of sizes and types. However, generally speaking, you’ll most often come across three variations. They are:
- Countertop – These are the most common and most affordable microwave ovens. You can plug them in and use them right after unboxing.
- Built-in – Built-in microwave ovens will typically require a professional installer, and once installed, you won’t be able to move them yourself should you ever need to. However, the countertop space they save deems them to be worth the extra costs.
- Over-the-range – These microwave ovens are installed above a range and can also save you some countertop space. Moreover, they draw the odors and smoke coming from the cooktop beneath, filter them, and then exhaust them.
The sizes of these microwave ovens are measured in inches for the external dimensions and in cubic feet for the internal dimensions.
The following table takes a closer look at the 4 most common sizes of microwave ovens and their wattage:
| Size | Dimensions | Watts |
| Compact (0.7 cubic feet) | 17.3 x 10.1 x 14.1 inches (44 x 26 x 36 cm) | 700 watts |
| Mid-size (1.2 cubic feet) | 20.69 x 12.19 x 15.25 inches(53 x 31 x 39 cm) | 1200 watts |
| Full-size (1.6 cubic feet) | 21.8 x 19.2 x 13 inches(55 x 79 x 13 cm) | 1250 watts |
| Large (2.2 cubic feet) | 20 x 24 x 14 inches(51 x 61 x 36 cm) | 1200 watts |
The values given above reflect the standard sizes and wattage of most microwave ovens. Note that with some manufacturers, you may encounter variations in the dimensions and wattage of their products.
But in general, the larger a microwave oven, the higher its wattage. And a higher wattage corresponds to a faster cooking time.
Microwave ovens that run on 700 watts and below are far less efficient and will impact the quality of your cooking.
So, if you are in the market for a new appliance and are wondering what wattage to go for, set the benchmark at a decent 1,000 watts. This is enough power for it to operate efficiently.
Take note, however, that ovens with higher wattages also fall under higher price ranges.
What Affects Microwave Usage
The Wattage
There’s no shortage of microwave oven manufacturers and models, and each of the latter has its own power requirements.
As we have already seen, the size of a microwave oven largely determines how much power it needs to operate.
More sizable ovens have a higher wattage and are more efficient than their smaller counterparts with lower wattage.
However, this efficiency does come at a cost, with the higher wattages translating to higher power consumption.
This chart below gives an average overview of a microwave oven’s wattage and its corresponding capacity:
| Microwave Oven Capacity (in liters) | Microwave Oven Wattage |
| 20 liters | 800 watts |
| 23 liters | 1,150 watts |
| 28 liters | 2,900 watts |
Moreover, the features and program settings that microwave ovens come with also have a bearing on the appliance’s power consumption.
Some of the program settings you’ll find in a microwave oven include but are not limited to the following:
- Add 30 seconds
- Popcorn
- Pizza reheat
- Beverage
- Soup
- Potato
- Dinner plate
- Frozen entree
- Frozen vegetables
- Fresh vegetables
You may find variations to these depending on the brand and model of the appliance. However, a more standardized approach is to use a microwave oven’s power levels.
These levels are designated by percentage with increments of 10%. But the following are the benchmarks:
- High – 100%
- Medium-High – 70%
- Medium – 50%
- Medium-Low/Defrost – 30%
- Low – 10%
Because power levels are similar across different manufacturers, recipes typically indicate the power level required for cooking. Directions on the labels of food items also do the same.
Needless to say, operating at higher power levels also results in more power consumption.
The Type of Food
Perhaps the key selling point of the microwave oven is the speed at which it can heat or cook food. What a regular oven takes hours to complete, a microwave can do in mere minutes.
However, the rate at which this happens varies by the type of food, with the moisture, thickness, or layers of a certain dish or ingredient being the factors affecting this.
Foods with more moisture heat faster because the moisture absorbs the radiation. The layers of the food are also something to consider. The thicker the food item being reheated, the more time the radiation will take to penetrate the inner layers.
Popping these types of food in a microwave oven will require your appliance to operate longer and consequently consume more power.
Energy Suppliers & the Difference in Price
Since Percy Spencer’s invention started selling in 1946, the microwave oven has been a must-have appliance and remains so today.
Along with refrigerators and cooking ranges, a microwave oven is a feature you would expect to find in the kitchen of any home. However, the price for running one varies by home, or more specifically, by state.
To begin with, a kilowatt hour (kWh) is the measurement for energy used. The average cost across the United States is 13.31 cents per kilowatt hour, but there are considerable disparities by state.
For instance, residents of Lousianna are charged an easy 9.53 cents per kWh compared to the 32.76 cents per kWh that residents of Hawaii have to pay.
That being the case, your state of residence also factors into the figures reflected on your electric bill.
How Much Does It Cost To Run a Microwave Oven
Microwave ovens have provided us with an easier way to prepare meals and have also freed up a lot more time for us. But what exactly does it cost to run this miracle kitchen appliance?
The answer will significantly vary depending on the wattage of the microwave oven, the operational time, and the electricity tariff or cost per kilowatt hour in your state of residence. To give you a clearer idea, it would cost an average of $0.16 to operate a 1,200 watts microwave oven for 1 hour.
Now, your electricity bill will not be able to give you a specific answer. That’s because the kilowatt hour reflected on it is compounded by all the other appliances, electronics, and lights.
Basically, anything that you have plugged in within the month contributes to that number on your bill. However, the kilowatt hour quantity is not broken down and attributed to the individual power consumer.
Still, you can easily determine the specifics of your microwave oven’s power consumption. You just need to know your appliance’s wattage, the amount of time you use it, and the electricity tariff or cost of a kilowatt hour in the state you live in.
There are two equations you will need for your calculations:
- Power consumed by microwave oven (kWh) = Rated Power (Watt) X Operational Hours (hrs)
- Electricity bill for using a microwave oven = Power Consumption X Electricity Tariff
Take, for instance, a 1,200 watts microwave oven used for a total of one hour a day with a 13.31 cents (national average) cost per kilowatt hour.
Follow these steps to determine the power consumption and cost of your microwave oven:
- Multiply the rated power in watts (1,200) by the number of operational hours (1): 1,200 watts X 1 hour = 1,200 watt hour.
- Multiply the watt hour value by 0.001 to obtain the kilowatt hour value: 1,200 watt hour X 0.001 = 1.2 kWh
- Multiply the kilowatt hour value (1.2 kWh) by the electricity tariff (13.31 cents): 1.2 kWh X 0.1331 = $0.16.
Note that you should use decimals when accounting for operational times that are less than one hour. That would be:
- 15 minutes – 0.25
- 30 minutes – 0.5
- 45 minutes – 0.75
For quick reference, I’ve included the following chart that reflects the kilowatt hour and cost for 15 minutes, 30 minutes, 45 minutes, and 1 hour of microwave oven usage.
| Time | Watts | kWh | Cost |
| 15 minutes | 700 watts | 0.18 | $0.02 |
| 30 minutes | 700 watts | 0.35 | $0.05 |
| 45 minutes | 700 watts | 0.53 | $0.07 |
| 1 hour | 700 watts | 0.70 | $0.09 |
| 15 minutes | 1,000 watts | 0.25 | $0.03 |
| 30 minutes | 1,000 watts | 0.50 | $0.07 |
| 45 minutes | 1,000 watts | 0.75 | $0.10 |
| 1 hour | 1,000 watts | 1.0 | $0.13 |
| 15 minutes | 2,000 watts | 0.30 | $0.04 |
| 30 minutes | 2,000 watts | 0.60 | $0.08 |
| 45 minutes | 2,000 watts | 0.90 | $0.12 |
| 1 hour | 2,000 watts | 1.2 | $0.16 |
Alternatively, you can determine the power consumption of your microwave oven with an electricity usage monitor.
These are devices that measure energy consumption of other electrical appliances. They typically have a socket in which you plug the appliance you want to monitor, and then you plug the device directly into the wall power source for a reading.
If you are thinking of getting one, the Poniie PN2000 Plug-in Kilowatt Electricity Usage Monitor (available on Amazon.com) is an excellent option. It’s both an Amazon’s Choice product and a best seller.
Tips for Saving Money With a Microwave Oven
Clean It Regularly
Cleaning your microwave oven doesn’t just get rid of the unsightly food splatters and unpleasant odors. It ultimately affects how efficiently your appliance operates.
Warm air needs to circulate freely inside a microwave oven as you reheat or cook up a meal. However, the caked-on splatters from previous meals can pose a hindrance to this circulation and result in the food not being heated as thoroughly as before.
Consequently, you would have to extend the cooking time, which means more power consumption and more kilowatt hours to pay for.
In addition, a dirty roller guide will prevent your microwave table from turning as smoothly or at the same rate as it should. The unevenly heated food resulting from this would likely require an additional spin in the microwave oven. This will contribute to increased figures on your electricity bill.
That said, a regular cleaning of your microwave oven certainly ensures that it isn’t repulsive to the sight or smell and that bacteria breeding in the interior does not pose any health hazards.
But more than this, wiping your microwave oven every day (when it’s used) allows it to keep operating efficiently and does away with those cooking time extensions.
That means well-heated meals on the first go and kilowatts and cents saved.
Unplug It When Not in Use
We’ve heard it time and time again. Unplugging electronics and appliances can help save energy. A study specifically on microwave ovens can even attest to this.
In recent times, however, the advances in technology have allowed for redesigns of power supplies, making them more efficient and resulting in an impressive 90 percent reduction of stand by power.
So, does unplugging your electronic devices still make a difference?
Not a significant one. However, anything that is plugged in still expends kilowatt hours, albeit 90 percent less than in previous decades.
That 10 percent you do spend on may seem inconsequential from a daily or monthly standpoint. But over time, it will translate to a considerable figure.
Unplugging electronic devices does save energy. Doing the same with your microwave oven when it’s not in use is hardly an inconvenience and will unquestionably save you electricity and its subsequent costs in the long run.
Most Popular Microwave Ovens
The microwave oven was a game-changing invention. And in the decades since its eureka moment, this appliance has been evolving with every technological advance, urged on by different manufacturers putting their own spin on it.
If you are looking to buy your first microwave oven or upgrade from an old appliance, the currently most popular microwave ovens on the market for your consideration are charted below.
The similarities among these Amazon’s Choice and best-selling models of microwave ovens are few and far between, as I wanted to provide you with a diverse range of options.
| Microwave Oven | Capacity | Price | Pros | Cons |
| BLACK+DECKER Digital Microwave with Turntable | 0.9 cu. ft | $114.99 | Child-safety lock, Fits into small spaces | Less capacity, Noisy operation |
| Sharp ZSMC1449FS | 1.4 cu. ft | $159.99 | Smart microwave oven, Over 70 Alexa voice commands | Echo device needed for voice commands |
| Panasonic NN-SN936B | 2.2 cu. ft | $266.88 | Large capacity good for families, Inverter technology, Touchscreen, Smart cooking, Keep warm feature | Stiff buttons |
Highly rated models are a good bet when shopping for appliances. However, remember these key considerations before adding anything to your cart:
- Capacity
- Dimensions
- Power consumption
All the rest are bonuses. You will be thankful you took the time to pick out a microwave oven that is suited to your cooking needs, kitchen space, and electricity expense budget.
Hi all! I’m Cora Benson, and I’ve been blogging about food, recipes and things that happen in my kitchen since 2019.