Microwave
How much electricity does a microwave use?
Wall draw 1,200–1,800 W · ~10 min/day · under $2 per month
A microwave's cooking power (800–1,200 W) is not the same as what it draws from the wall. Magnetron efficiency peaks around 65–70%, so a 1,000 W microwave typically pulls 1,400 W while running. That sounds alarming until you notice it runs for four minutes.
Put it in perspective
Ten minutes a day at 1,400 W is 0.23 kWh per day — about 7 kWh a month, or $1.16 at average US rates. A space heater does that in three hours.
Where the quiet waste is
Two things actually consume energy here: the clock and the display, which draw 1–3 W continuously (roughly $1–$4 a year), and the incandescent bulb inside older units, which stays on the whole time the door is open. Neither is worth changing hardware over, but if you are buying new, inverter microwaves use noticeably less.
Does defrost cost more?
Yes. Defrost cycles repeatedly cycle the magnetron at lower duty, which is less efficient than continuous heating. Defrosting overnight in the fridge uses more fridge energy but less microwave energy — the total is usually a wash.
Frequently asked questions
How many watts does a microwave use?
Wall draw 1,200–1,800 W. The figure on the rating label is the maximum draw; actual use varies with settings, age and usage pattern.
How much does it cost to run a microwave per month?
With the defaults above it comes to the monthly figure shown in the calculator. At 16.5¢/kWh — the US residential average — that is a realistic middle estimate. Your own bill may be 30% lower or higher depending on state.
Is it cheaper to run a microwave at night?
Only if your utility offers a time-of-use plan and you avoid the 4pm–9pm peak window. On a flat-rate plan, the time of day makes no difference to the total.
Does the calculator account for real-world duty cycles?
Not automatically — you enter the effective hours yourself. For compressing appliances like refrigerators and AC units, enter the running watts and roughly the proportion of time the compressor is on, which is usually 30–50%.
Will a newer microwave actually save money?
Compare the kWh figure in the calculator against an Energy Star model's stated annual use. If the difference is a few hundred kWh a year, the payback on a replacement is usually long; if it is over 500 kWh, it is worth pricing out.