Generator Wattage Chart: Appliance Running and Starting Watts
Most homes get through an outage on 2,550 running watts (refrigerator, lights, a sump pump and the furnace blower), which a generator rated at 3,500 running watts covers. The chart below lists the running and starting watts of each appliance. Tick your own in the generator size calculator to total them.
Part of the project planner: Planning backup power, batteries and solar.
Appliance wattage chart
Running watts are the steady draw. Starting watts are the brief surge when a motor switches on. Typical values: check the label on yours.
| Appliance | Running watts | Starting watts |
|---|---|---|
| Refrigerator | 700 | 2,200 |
| Freezer | 500 | 1,500 |
| Sump pump, 1/3 hp | 800 | 2,100 |
| Well pump, 1/2 hp | 1,000 | 2,100 |
| Furnace blower, 1/2 hp | 800 | 2,350 |
| Window air conditioner, 10,000 BTU | 1,200 | 3,600 |
| Central air conditioner, 2 to 3 ton | 3,500 | 10,500 |
| Electric water heater | 4,000 | 4,000 |
| Microwave | 1,000 | 1,000 |
| Coffee maker or kettle | 1,000 | 1,000 |
| Dishwasher | 1,500 | 1,500 |
| Washing machine | 1,150 | 2,300 |
| Electric dryer | 5,400 | 6,750 |
| Garage door opener | 550 | 1,100 |
| Space heater | 1,500 | 1,500 |
| Fans | 150 | 300 |
| LED lights, about 10 bulbs | 100 | 100 |
| TV and cable box | 250 | 250 |
| Laptop, router and phone chargers | 150 | 150 |
What generator size does each load need?
These are the sums from the same chart, with the headroom the calculator adds:
| Load | Running watts | Peak watts | Generator to shop for |
|---|---|---|---|
| Basic outage: refrigerator, lights, laptop and router | 950 | 2,450 | 2,000 running watts |
| Basic plus sump pump and furnace blower | 2,550 | 4,100 | 3,500 running watts |
| Add well pump, microwave, coffee maker and TV | 5,800 | 7,350 | 7,500 running watts |
| Add a window air conditioner | 7,000 | 9,400 | 9,000 running watts |
| Add central air conditioning | 9,300 | 16,300 | 15,000 running watts |
| Add central air, electric water heater and dryer | 18,700 | 25,700 | Over 22,000 W: whole-home standby generator |
How to use the chart
- Add the running watts of everything you want on at the same time.
- Add the biggest surge: only one motor starts at a time, so add just the largest gap between its starting and running watts.
- Leave headroom. A generator run flat out is loud, thirsty and short-lived, so pick a size above the total.
- Skip the big heaters if you can: an electric water heater, dryer or central air conditioner can double the size you need.
A load above what a portable unit handles points to a standby generator: see what size standby generator you need. For a battery instead of a generator, try the power station size calculator, and for amps use the watts to amps calculator.
The full explanation is in what size generator do I need. These are estimates: have an electrician connect any generator to your house wiring through a transfer switch.
Frequently asked questions
What is a generator wattage chart?
A list of how many running watts each appliance uses and how many starting (surge) watts a motor needs for a moment when it switches on. Add the running watts of everything you want on at once, then allow for the biggest surge.
How many watts does a refrigerator need on a generator?
About 700 running watts and 2,200 starting watts. The compressor surges when it cycles on.
How many watts does a central air conditioner need?
About 3,500 running watts and 10,500 starting watts for a 2 to 3 ton unit, which is why central air usually calls for a standby generator.
What is the difference between running and starting watts?
Running watts are what an appliance draws steadily. Starting watts are a short surge, mostly in motors and compressors, that can be two to three times higher.
Are these exact wattages?
No. They are typical values. The nameplate on your appliance, usually in watts or in amps and volts, is the number to trust.
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Estimates only. Quantities depend on your materials, site and supplier. Confirm important numbers before you order, and follow local building codes for anything structural.