What size generator do I need for my home?

The generator size you need depends on which appliances you want to power. Add up the running watts of all appliances, account for the highest surge wattage, then add 20% buffer. Most homes need 3,000-7,500 watts for essential circuits.

What is the difference between running watts and starting watts?

Running watts (rated watts) is the continuous power needed to keep an appliance running. Starting watts (surge watts) is the extra power needed for 1-2 seconds when a motor starts. Appliances with motors like refrigerators, AC units, and power tools can require 2-3x their running watts to start.

How do I calculate watts from volts and amps?

Watts = Volts × Amps. For US household appliances, most use 120 volts. Check the appliance label for the amp rating, then multiply by 120 to get watts. For example, a 5 amp appliance uses 600 watts (120V × 5A = 600W).

Generator Size Calculator - Find the Right Generator for Your Power Needs

Choosing the right generator size is essential for reliable backup power. A generator that's too small won't run all your appliances, while one that's too large wastes fuel and money.

Running vs. Starting Watts

Running watts is continuous power needed. Starting watts is the surge when motors start (2-3× running watts for fridges, ACs, pumps).

Common Sizes

2-3kW: Camping, small tools
3-5kW: RV, essential home circuits
5-7.5kW: Most home backup needs
7.5-10kW: Larger homes, well pumps
10kW+: Whole-house, central AC

Generator Calculator

What Size Generator Do I Need?

Select Appliances

How to Calculate Generator Size

Running vs. Starting Watts

Common Sizes

Generator Calculator