What Size Generator
Do You Need?
Start with what you want to keep running. Add your appliances below, check their wattage, and get a size estimate you can use when comparing generators.
What do you want to keep running?
Tap an appliance to add it. You can add the same one more than once.
The starting list and appliance buttons use example wattages. Replace them with the numbers from your appliance label or manual. For a microwave, use its electrical input watts, not its cooking watts.
Check your numbers
Enter watts for one appliance. The quantity does the multiplying.
Running watts are what an appliance uses while it is on.
Starting watts are the total power it needs for a moment when it turns on. If it has no extra startup demand, enter the same number in both boxes. Do not guess for a pump, refrigerator, or air conditioner.
Volts: most ordinary plug-in devices use 120V. Some well pumps and larger appliances need 240V. Check the appliance label.
| Appliance | Qty. | Running W | Starting W | Volts | Remove |
|---|---|---|---|---|---|
Choose how you will use it
The result uses the fuel and settings you choose here.
Extra room means choosing a generator with a little more power than your list needs, instead of using every available watt. The 25% setting is an example allowance.
A generator often makes less power on propane or natural gas. Your appliance total stays the same; the matching models below use the generator ratings for your chosen fuel.
We’ll compare the generators on this site with your wattage, fuel, and voltage needs.
A few things watts will not tell you
Check each outlet, breaker, cord, and home connection. A generator can have enough total power while a single outlet has a lower limit. For home wiring, well pumps, central air, or equipment you depend on for your health, have the equipment supplier or an electrician check the full setup. Hot weather, high elevations, and how long an appliance takes to start can reduce what a generator can handle.