How Much Does It Cost to Run a Microwave? | Cents Per Session

A 1,000-watt microwave costs about 5.5 cents for 18 minutes at the current U.S. average residential rate of 18.31 cents per kilowatt-hour.

At that rate, a mid-size microwave in daily use adds roughly $13 a year in heating energy — far less than the fridge, dryer, or water heater. The number shifts with only two things: the appliance’s rated input wattage and your utility’s price per kWh. Connecticut households pay about 63% more per kWh than Washington households, so the same oven can cost one family twice what it costs another.

How to Calculate Microwave Running Cost From Your Own Label

Multiply the microwave’s electrical input in kilowatts by the hours it runs, then by your utility’s price per kWh.

One detail trips people up: microwaves carry two wattage numbers. Cooking output is what the marketing lists (“700W”), while electrical input is what the wall socket delivers. Input runs higher because the magnetron, cooling fan, turntable motor, and control board all draw power. Check the label on the back or the owner’s manual for the input rating, then divide by 1,000 to get kilowatts.

Then convert run time to hours. Ten minutes is 0.167 hours, and 30 minutes is 0.5 hours — not 0.30. That decimal slip alone inflates estimates by more than half. Multiply kilowatts by hours by your rate, and you have the cost of that session.

If you’re shopping for a replacement and want to factor wattage into the decision, this roundup of tested budget microwaves with real wattage specs pairs input ratings with current pricing so the math starts from a real number.

What Different Wattages and Session Lengths Actually Cost

An hour of continuous heating on a 1,000-watt oven costs about what a single light bulb running all evening would. The biggest line item in a microwaved dinner is the food, not the electricity.

Rates swing by state. At those extremes, the same 18-minute session costs roughly 4.3 cents in Washington and 7.0 cents in Connecticut. Time-of-use customers may pay different prices depending on the hour they cook.

Yearly Cost, Standby Draw, and What the Estimates Leave Out

At 71 hours of heating per year — the operating-time benchmark the U.S. Department of Energy used in its microwave standby analysis — a 1,000-watt oven runs about $13.00 annually, with 700-watt models near $9.10 and 1,200-watt models near $15.60.

Those totals cover active heating only. A plugged-in microwave keeps drawing power for its clock, display, and touchpad sensors, which the Department of Energy treats as a separate category. That idle draw is small per hour but accumulates across 8,700 hours a year. For an exact figure, a plug-in electricity meter rated for the oven’s voltage and current gives it — record wattage while heating, then apply your utility’s rate. The EIA’s monthly electricity end-use data supplies the rate that anchors every calculation here.

Don’t assume the microwave dominates a meal’s energy footprint. A 10-minute reheat is a rounding error against an hour of oven time. Do follow the manufacturer’s instructions and local electrical code — countertop, over-the-range, and built-in models differ in voltage and current draw, and extension cords or overloaded circuits are a fire risk. Never run a microwave empty unless the manual explicitly allows it.