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Whole-Home Load Sizer
Size a backup generator or battery by your real appliance load, surge included.
🇺🇸 Figures use US units (watts, sq ft) and 120/240 V conventions.
1 · What are you backing up?
2 · Fine-tune your loads
3 · Your outages
Your result
Running
0W
Peak surge
0W
Recommend
0W
✓
Sized for the single largest surge, not the sum. We add every appliance's running watts, then add only the biggest single startup surge — the method reputable manufacturers use. Adding up every surge (what many calculators do) inflates the number and pushes you toward a bigger, costlier generator than you need.
Pick appliances to see your sizing.
Recommended units
Fuel & run-time estimator
Fuel figures are load-dependent estimates (50% load burns ~65% of full-load rate, not 50%), anchored to published consumption rates. Actual use varies with generator model, age, altitude, temperature, and how much you run at once. Container counts assume ~5 gal gas cans and ~4.7 usable gal per 20-lb propane tank.
Estimates for planning; confirm with a licensed electrician before purchase or installation.