Generator sizing / By size
What will a 3,500 watt generator run?
We treat 3,500 W as the most it can put out, start-up surge included. That's how most generators are sold.
Short answer
A 3,500 watt generator runs the basics plus a microwave, with 338 W to spare when the biggest motor starts. Switch things on one at a time and it can also carry the basics, freezer, sump pump and furnace fan. It won't run a well pump or central air with the basics.
What a 3,500 watt generator runs in an outage
| What's on | Running | At start-up | Verdict |
|---|---|---|---|
| Fridge, 6 LED bulbs, TV and Wi-Fi | 462 W | 1,662 W | Runs it 1,838 W to spare at start-up |
| The basics plus a freezer | 562 W | 1,762 W | Runs it 1,738 W to spare at start-up |
| The basics plus a microwave | 1,962 W | 3,162 W | Runs it 338 W to spare at start-up |
| The basics, a freezer and a sump pump | 1,612 W | 3,762 W | Runs it, with care Switch things on one at a time |
| The basics, a freezer and the furnace fan | 1,437 W | 3,787 W | Runs it, with care Switch things on one at a time |
| The basics plus a window AC | 1,962 W | 4,162 W | Runs it, with care Switch things on one at a time |
| The basics, freezer, sump pump and furnace fan | 2,487 W | 4,837 W | Runs it, with care Switch things on one at a time |
| The basics plus a 1 HP well pump | 2,462 W | 8,462 W | Won't run it 6,000 W to start the well pump |
| The basics plus a 3 ton central AC | 5,862 W | 13,062 W | Won't run it 2,362 W short running |
The basics are a fridge, 6 LED bulbs, a TV and a modem. Start-up is everything running plus the biggest single motor's surge, the same math as the generator sizing calculator. Click a row to open it there and add your own things.
Item by item
On its own, a 3,500 watt generator can start 17 of the 23 things on our list. It can't start electric dryer, well pump, central AC, electric water heater, air compressor or table saw.
| Item | Running | Starting | Alone |
|---|---|---|---|
| Refrigerator | 192 W | 1,200 W | Starts |
| Freezer | 100 W | 1,000 W | Starts |
| Microwave (1,000 W) | 1,500 W | 1,500 W | Starts |
| Coffee maker | 600 W | 600 W | Starts |
| Electric range burner (8 in) Needs 240V | 2,100 W | 2,100 W | Starts |
| TV (46 in flat screen) | 190 W | 190 W | Starts |
| Laptop | 250 W | 250 W | Starts |
| Modem or router | 20 W | 20 W | Starts |
| LED bulbs | 10 W | 10 W | Starts |
| Washer | 1,200 W | 1,200 W | Starts |
| Electric dryer Needs 240V | 5,400 W | 6,750 W | Too big |
| Sump pump (1/2 HP) | 1,050 W | 2,150 W | Starts |
| Well pump (1 HP) | 2,000 W | 6,000 W | Too big |
| Furnace fan (1/2 HP) | 875 W | 2,350 W | Starts |
| Window AC (10,000 BTU) | 1,500 W | 2,200 W | Starts |
| Central AC (3 ton) | 5,400 W | 7,200 W | Too big |
| Space heater | 1,300 W | 1,300 W | Starts |
| Electric water heater Needs 240V | 4,500 W | 4,500 W | Too big |
| Garage door opener | 720 W | 1,420 W | Starts |
| Air compressor (1 HP) | 1,600 W | 4,500 W | Too big |
| Circular saw (7-1/4 in) | 1,400 W | 2,300 W | Starts |
| Table saw (10 in) | 1,800 W | 4,500 W | Too big |
| Battery charger (15 A) | 380 W | 380 W | Starts |
Watts are typical figures from Honda's wattage guide, then Briggs & Stratton, Champion and DuroMax. The real number is on each thing's nameplate. A 240V load also needs a 120/240V generator and a transfer switch.
Generators around 3,500 watts
- Honda EU3200i: 2,600 W running, 3,200 W starting, 120V only
Other sizes
Smaller: what a 2,000 watt generator runs. Bigger: what a 5,000 watt generator runs. Not sure what size you need? Start from your list in the generator sizing calculator.
Never plug a generator into a wall outlet to power the house. Use a transfer switch or an interlock kit, wired by an electrician.