What size generator do I need for my house?
Tick what you want to run at the same time. Edit the watts to match your appliance labels.
How this is calculated
Formula: Peak watts = sum of running watts + the single largest extra starting watts, then add a buffer (20% is common).
Assumptions: Only one motor starts at a time. Wattages are typical values; your appliance label or manual is more accurate. Motors (fridges, pumps, AC) need 2–3× their running watts for a second or two when starting.
Frequently asked questions
Why only add the biggest starting watts?
Motors rarely start at the exact same moment, so you only need room for the largest single surge on top of everything already running.
Can a generator run a whole house?
Large standby units can. Portable generators of 3,000–7,500 W usually cover essentials like the fridge, lights, sump pump and furnace fan.
Should I size for running or starting watts?
Both. The generator's running rating must cover the running total, and its starting (surge) rating must cover the peak.
Is it safe to plug a generator into a wall outlet?
No. Backfeeding is dangerous and illegal in most places. Use a transfer switch installed by an electrician, and never run a generator indoors or in a garage.