What Can a 4,000-Watt Generator Run?
A 4,000-watt portable generator usually delivers about 3,200 running watts, with 4,000 watts available for a second or two while a motor starts. To keep it from running flat out, plan on a steady load of about 2,667 watts. Generators this size usually have no 240-volt outlet, so well pumps and central AC are out.
Common combinations
Each row assumes everything in it runs at once, with the biggest motor starting while the rest are on.
| Load | Running W | Starting peak W | Fits? |
|---|---|---|---|
| Fridge, freezer, lights and Wi-Fi | 790 | 1,990 | Yes |
| Same, plus a 1/2 HP sump pump | 1,840 | 3,040 | Yes |
| Gas furnace, fridge, lights and TV | 1,440 | 2,640 | Yes |
| Well-water home essentials (1/2 HP well pump) | 1,790 | 2,990 | No |
| Essentials plus a window AC | 1,640 | 3,440 | Yes |
| Essentials plus 3-ton central AC | 5,080 | 11,380 | No |
| Whole house with gas heat and gas appliances | 10,905 | 19,105 | No |
| Whole house, all-electric | 21,730 | 29,930 | No |
Runs on its own
- Sump pump (1/3 HP)
- Sump pump (1/2 HP)
- Refrigerator
- Freezer (chest or upright)
- Microwave
- Coffee maker
- Dishwasher
- Gas furnace blower (1/3 HP)
- Gas furnace blower (1/2 HP)
- Boiler, gas or oil (burner + circulator)
- Window AC (10,000 BTU)
- Space heater
- Dehumidifier
- LED lighting (whole house)
- Wi-Fi router + modem
- TV
- Computer + monitor
- Phone & laptop chargers
- Garage door opener (1/2 HP)
- Washing machine
- Gas dryer
- CPAP machine
- Oxygen concentrator
Too big on its own
- Well pump (1/2 HP) (needs a 240-volt outlet)
- Well pump (3/4 HP) (needs a 240-volt outlet)
- Well pump (1 HP) (needs a 240-volt outlet)
- Electric cooktop (2 burners) (needs a 240-volt outlet)
- Central AC or heat pump (2 ton) (needs a 240-volt outlet)
- Central AC or heat pump (3 ton) (needs a 240-volt outlet)
- Central AC or heat pump (4 ton) (needs a 240-volt outlet)
- Central AC or heat pump (5 ton) (needs a 240-volt outlet)
- Electric dryer (needs a 240-volt outlet)
- Electric water heater (needs a 240-volt outlet)
- EV charger (Level 2) (needs a 240-volt outlet)
Cost and fuel
A 4,000-watt portable generator typically costs $500–$1,000. To power circuits in your home rather than running extension cords, add an inlet box and a transfer switch or breaker interlock installed by an electrician, usually $600–$1,800.
At a steady 2,667-watt load it burns roughly 0.34 gallons of gasoline an hour, or about 8 gallons a day if it runs around the clock. Lighter loads use less. Store fuel safely and plan how you'll refill during a long outage.
Have a different list? Run the calculator with your own appliances. Nearby sizes: 3,500 W · 5,000 W.