A generator wattage chart lists the running watts each appliance needs to keep working and the extra starting watts that motor-driven appliances draw for a few seconds when they switch on. A typical refrigerator, for example, runs on about 400 to 700 watts but needs roughly 2,200 extra watts to start, according to the charts published by Champion Power Equipment and the Eugene Water & Electric Board (EWEB).
Use the generator wattage chart below to add up your own loads, then check the worked examples for 2,200, 3,000, 7,000 and 13,000-watt generators. Chart values are typical figures. The wattage on your appliance’s nameplate or in its manual is always the better number.
Generator wattage chart for common appliances
| Appliance | Running watts | Extra starting watts | Source |
|---|---|---|---|
| LED light bulb (15 W) | 15 | None | EWEB |
| Phone charger | 20 | None | EWEB |
| Laptop | 60 | None | EWEB |
| Color TV | 400 | None | EWEB |
| Computer with monitor | 800 | None | EWEB |
| Refrigerator/freezer | 700 | 2,200 | EWEB |
| Refrigerator | 400 | 2,200 | Champion |
| Microwave (625 W / 1,000 W) | 625 / 1,000 | None | EWEB |
| Coffee maker | 1,000 | None | EWEB |
| Toaster | 850 | None | EWEB |
| Toaster oven | 1,200 | None | EWEB |
| Air fryer | 1,500 | None | Champion |
| Electric stove | 2,000 | None | Champion |
| Dishwasher | 1,200 | 1,500 | Champion |
| Washing machine | 500 | 1,200 | Champion |
| Electric dryer | 1,000 | 3,000 | Champion |
| Furnace fan blower (1/3 HP) | 700 | 1,400 | EWEB |
| Sump pump (1/3 HP) | 800 | 1,300 | EWEB |
| Sump pump (1/2 HP) | 1,050 | 2,200 | EWEB |
| Water well pump (1/3 HP) | 1,000 | 2,000 | EWEB |
| Space heater | 1,500 | None | EWEB |
| Window AC (12,000 BTU) | 3,250 | 3,950 | EWEB |
| Electric water heater | 4,500 | None | EWEB |
| Central AC (3-ton) | 3,500 to 5,000 | Up to 15,000 to 18,000 to start | Generac |
The two charts do not always agree. Champion lists a refrigerator at 400 running watts and a window air conditioner at 1,200 running and 2,000 starting watts, while EWEB lists a 12,000 BTU window unit at 3,250 and 3,950. Appliance size and age explain most of the spread, so read your own nameplate before you buy.
How to size a generator with the chart
- List everything you want to run at the same time and add up the running watts.
- Find the single appliance with the highest extra starting watts and add that number to the running total. Both EWEB and Champion use this method.
- Choose a generator whose running (rated) watts cover step 1 and whose peak (starting) watts cover step 2.
Generac notes that motors typically need two to three times their running wattage to start, which is why a refrigerator or pump, not the toaster, usually decides the size. Starting motors one at a time, before you add other loads, also helps.
What can a 2,200 watt generator run?
Models: the Honda EU2200i (2,200 W maximum, 1,800 W rated), the DuroMax XP2300iH (2,300 peak, 1,800 running on gasoline) and the Tomahawk 2000W inverter (2,200 starting, 2,100 rated).
Example: six LED bulbs (90 W), a TV (400 W), a laptop (60 W), two phone chargers (40 W) and a coffee maker (1,000 W) total 1,590 running watts, inside the 1,800-watt rating. A 1/3 HP sump pump on its own needs 800 + 1,300 = 2,100 watts to start, close to the limit. A refrigerator is borderline: chart values put its start at 2,600 to 2,900 watts, although Honda markets the EU2200i for running an extra refrigerator, so check your fridge’s actual draw. If you need more, the Honda EU2200-KIT pairs two units in parallel for up to 4,400 watts.
What can a 3,000 watt generator run?
Models: the Honda EU3000iS (3,000 W maximum, 2,800 W rated) and the Honda EU3200i (3,200 W maximum, 2,600 W rated).
Example: a 1/3 HP furnace fan (700 W), six LED bulbs (90 W), a TV (400 W), a laptop (60 W) and two phone chargers (40 W) add up to 1,290 running watts. Adding the furnace fan’s 1,400 starting watts gives 2,690, which fits. A refrigerator alone needs about 2,900 watts to start by EWEB’s figures, so start it first while other loads are off, and keep the running total low when its compressor cycles. Honda says the EU3000iS can run a furnace, refrigerator or microwave and most 13,500 BTU RV air conditioners. RV owners can read what size generator for an RV.
What can a 7,000 watt generator run?
Models: the Honda EU7000iS (7,000 W maximum, 5,500 W rated, 120/240 V), the Tomahawk 7000W (7,000 max, 6,500 rated), the Simpson SPG7085E (8,500 starting, 7,000 running) and the diesel Kubota GL7000 (7.0 kW standby, 6.5 kW prime).
Example: a refrigerator (700 W), a separate freezer (700 W), a 1/2 HP sump pump (1,050 W), a 1/3 HP well pump (1,000 W), a 1/3 HP furnace fan (700 W), ten LED bulbs (150 W), a TV (400 W) and a laptop (60 W) total 4,760 running watts. Adding the largest extra starting load, 2,200 watts, gives 6,960 watts. That fits a 7,000-watt generator and stays under the EU7000iS’s 5,500-watt rating once everything is running.
What will a 13,000 watt generator run?
Models: the DuroMax XP13000HXT, XP13000HX and XP13000E (13,000 peak, 10,500 running on gasoline) and the Generac GP Series 12,500W tri-fuel (12,500 starting, 9,500 running on gasoline).
Example: everything in the 7,000-watt example (4,760 W) plus a 12,000 BTU window AC (3,250 W) and a 1,000-watt microwave comes to 9,010 running watts. The window AC’s 3,950 extra starting watts bring the peak to 12,960, just inside 13,000. Swap the AC for a 4,500-watt electric water heater and you get 10,260 running watts and a 12,460-watt peak, still within the rating. Output is lower on propane: DuroMax rates the XP13000HXT at 10,000 running watts on propane and 9,000 on natural gas. A 3-ton central air conditioner can need 15,000 to 18,000 watts to start, according to Generac, which is beyond these portables.
How many watts to run a house?
Running a whole house, including central air and kitchen appliances, is a job for a standby generator. Generac’s sizing guide suggests 10 to 14 kW with load managers for a home of about 1,550 square feet, and 18 to 22 kW for a home of about 2,000 square feet that wants whole-home coverage. Compare models on our standby generators page and read the home standby generator buying guide and whole house generator cost guide.
Choosing a generator for a well pump
EWEB lists a 1/3 HP well pump at 1,000 running watts plus 2,000 to start, so the pump alone needs about 3,000 watts. Check the pump’s nameplate voltage. If it is wired for 240 V, you need a generator with 240-volt output, such as the Honda EU7000iS, the DuroMax XP5500HX or the Honda EB5000. A hard-wired pump must be powered through a transfer switch installed by a licensed electrician. Never back-feed through an outlet: OSHA warns that connecting without a properly installed transfer switch can energize wiring for great distances and put utility workers at risk of electrocution. See our manual transfer switches and how to connect a generator to your house.
Whatever size you choose, CPSC advises running portable generators outside only, at least 20 feet from the home with the exhaust pointed away, and never in a garage, basement or shed.
Frequently asked questions
How many watts does a refrigerator use?
Typical charts list 400 to 700 running watts and about 2,200 extra watts to start the compressor. Your refrigerator’s nameplate or manual gives the exact figure.
How many watts does it take to run a house?
Essentials such as a refrigerator, freezer, pumps, furnace fan and lights can fit within about 7,000 starting watts, as in the example above. Whole-home coverage with central air typically calls for an 18 to 22 kW standby generator in a 2,000 square foot home, according to Generac.
What size generator do I need for a well pump?
A 1/3 HP well pump needs about 3,000 watts to start by EWEB’s figures, plus whatever else is running. Larger pumps need more, and a 240 V pump needs a 240 V generator and a transfer switch.
Where do I find an appliance’s wattage?
Look for the label or nameplate on the appliance, usually on the back or bottom, or in the owner’s manual. Champion’s guide shows the wattage printed on the device label.