Short answer: the average US home uses about 865 kWh a month, which works out to an average draw of about 1,200 watts around the clock. But use is uneven: at peak moments, with the AC, oven and dryer running, a house can pull 5,000 to 10,000 W or more. To keep the essentials running in an outage, most homes need 3,500 to 5,000 running watts; to run nearly everything, including central air, plan on 10,000 to 20,000 W.
Tick the appliances you want to keep on in the generator size calculator to get your own figure.
Average watts vs peak watts
Two numbers matter, and they answer different questions:
- Average power tells you how much energy you use over time. 865 kWh a month ÷ 730 hours in a month ≈ 1.18 kW, or about 1,200 W. This is what you size solar panels and batteries for.
- Peak power is the most you draw at one moment. This is what a generator or battery inverter must be able to supply, including the brief start-up surge of motors such as fridge compressors, pumps and air conditioners.
In the UK, a typical home uses about 2,700 kWh a year: an average of only about 310 W. Australian homes average around 560 W and Canadian homes around 1,150 W, though homes with electric heating use far more in winter.
How many watts common appliances use
| Appliance | Running watts | Starting watts |
|---|---|---|
| Refrigerator or freezer | 700 | 2,200 |
| Sump pump (1/2 HP) | 1,050 | 2,150 |
| Well pump (1/2 HP) | 1,000 | 2,100 |
| Gas furnace fan (1/2 HP) | 800 | 2,350 |
| Window AC (10,000 BTU) | 1,200 | 1,800 |
| Microwave (1,000 W) | 1,000 | 1,000 |
| Space heater | 1,500 | 1,500 |
| Washing machine | 1,150 | 2,250 |
| Electric water heater | 4,000 | 4,000 |
| Electric clothes dryer | 5,400 | 6,750 |
| Central AC (3 ton) | about 3,000–3,500 | about 10,000+ without a soft starter |
| LED lights (10 bulbs) | 100 | 100 |
| Wi-Fi router and modem | 20 | 20 |
Running watts are typical figures from generator manufacturers' wattage guides; your appliance's label or manual has the exact number. Motors draw two to three times their running watts for a second or two at start-up.
How many watts to run a house in a power outage
| What you want to run | Running watts | Typical backup |
|---|---|---|
| Bare essentials: fridge, lights, internet, phones | about 900 | 2,000–3,000 W inverter generator or a large power station |
| Essentials plus sump pump and furnace fan | about 2,800 (4,300 starting) | 5,000 W portable generator |
| Add a well pump, microwave and window AC | 5,000–6,000 | 7,500 W portable generator |
| Most of the house, including central AC and an electric range | 10,000–20,000 | Whole-home standby generator |
You only need to cover the starting surge of the single largest motor, because motors rarely all start in the same second. That is how the generator calculator works: total running watts, plus the biggest extra start-up surge.
How to measure your own home
- From your bill: divide monthly kWh by 730 to get average kW. For 1,200 kWh a month that is about 1.6 kW.
- From a smart meter or utility app: many show hourly or 15-minute use. Your highest hour on a hot or cold day is a good guide to peak demand.
- From your panel: a home energy monitor clipped onto the main cables shows live watts.
Frequently asked questions
Will a 5,000 W generator run a house?
It runs the essentials (fridge, freezer, sump pump, furnace fan, lights, internet) but not central air, an electric water heater, dryer or range.
How many watts does a house use per day?
Energy per day is measured in kWh, not watts. The average US home uses about 28 kWh a day; a UK home about 7.4 kWh.
Can a battery run a whole house?
A 13.5 kWh home battery can run essentials for about a day, but most can only deliver 5 to 11.5 kW at once, so large loads like central AC may need two units. Try the battery runtime calculator.
How many solar panels do I need to power a house?
About 20 400 W panels for the average US home with 4.5 sun hours a day. See how many solar panels to power a house.
Sources
- US Energy Information Administration, how much electricity does an American home use? (about 865 kWh a month in 2024).
- Ofgem, average gas and electricity use (2,700 kWh a year).
- Appliance wattages from generator manufacturers' published wattage guides.
Checked October 22, 2026.
Try the Generator Size Calculator
What size generator you need: running and starting watts for the appliances you want to keep on.
No comments yet.