Generator Sizing Calculator & Guides

Work out what size generator you need — pick your appliances to get the running and starting watts, the recommended kW class, and matching models.

What Size Generator to Run a House
Whole-house sizing guide
Generator Sizing Calculator
Appliances → watts → kW
Generator Size Chart
Sizing chart by home & load
Generator Size for a 30-Amp RV
30-amp RV sizing
Generator Size for a Refrigerator & Freezer
Fridge + freezer sizing

gennyguide’s sizing tools turn your home into a wattage number you can actually shop with. The generator sizing calculator lets you check the appliances you want to keep running — air conditioner, refrigerator, furnace blower, well pump, sump pump, lights — and adds up the running and starting (surge) watts, then names the standby kW class or portable size that covers it. The appliance guides go deeper on the common questions: what size generator to run a whole house, a quick-reference sizing chart, a 30-amp RV, or just a refrigerator and freezer during an outage. Every figure is a planning estimate — confirm the exact load with an electrician before you buy or install.

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