Microwaves have become a common feature in most American homes, giving us one of the most convenient and cheapest power methods to heat up meals and snacks. But have you ever wondered how much electricity microwaves consume? October 8 is the filing anniversary of Percy Spencer’s 1945 patent for the microwave, making it a great time to explore this kitchen appliance and its effect on your power bill.

How do microwave ovens work?

Before diving into the electricity consumption of microwaves, it’s important to take a quick look at how the appliance actually works.

Microwave ovens use electromagnetic energy to cook food. Here is a simplified explanation of the microwaving process:

1. A magnetron in the appliance converts electricity from the power outlet into high-powered radio waves.
2. The magnetron blasts the radio waves through a channel into the food compartment.
3. The food spins on the turntable slowly so it cooks evenly.

The waves bounce off the metal walls inside the microwave. When they hit the food, the waves penetrate it and make the water molecules in the food vibrate faster. The vibrating creates energy, which is transferred to the food as heat. The faster the molecules vibrate, the hotter the food becomes.

How much energy do microwaves use?

Like most appliances, a microwave oven’s energy usage varies depending on its wattage.

Microwave manufacturer Whirlpool states that the ideal wattage for most microwaves is 1000 watts (W). This offers versatility in defrosting, reheating, and cooking. Smaller models in the 600W-900W range work well for smaller tasks like reheating leftovers and warming drinks, but you may need additional cooking time for larger tasks. Larger models can go up to 1700W or higher, making them very powerful.

In other words, the wattage of a microwave directly correlates to the amount of electricity it consumes when you use it.

To refresh your memory on how to measure electricity usage, a 1000W microwave uses 1000W (or 1 kW) of energy if run continuously for an hour.

How do you measure how much electricity it takes to microwave something?

To figure out exactly how much energy your microwave uses, you need a few pieces of information:

• Your microwave’s wattage (check the appliance’s product manual — or look for the wattage on the microwave itself)
• How many hours or minutes you use it per day
• Your Texas electricity rates [cents per kilowatt hour (kWh)]

Enter these items into the following equation:   

Cost per day = (Wattage/1000) x hours used x electricity price per kWh

• If you run this 1000W microwave for 1 hour a day, it will use 1 kWh.
• Multiply this by your electricity cost per kWh. If you pay 20¢ per kWh, it will cost you about 20¢ to use your microwave for 60 minutes a day. That translates to approximately $6 per month, or $72 per year.
• What if you only use your microwave for 10 minutes a day? That’s 1/6 of an hour, so divide your totals by 6. Ten minutes of microwave use a day equates to just $1 per month and $12 per year.

If math isn’t your thing, don’t worry — the Internet is here to help. You can plug your data into this online electricity cost calculator.

Any way you crunch the numbers, it’s clear that the microwave is one of the cheapest power methods for cooking. And for that, we have Percy Spencer to thank!

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