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Generator Wattage & Sizing Calculator

Calculate running and starting surge watts to size your whole-house or portable generator accurately. Prevent breaker trips with inductive motor surge analysis.

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Col statusCol applianceCol runningCol startingCol qtyCol actions
Refrigerator & Freezer (Inverter Compressor)
180 Unit watts600 Unit watts
1
Submersible Sump Pump (0.5 HP Inductive)
800 Unit watts2,150 Unit watts
1
Natural Gas Furnace Blower Motor (1/3 HP)
650 Unit watts1,600 Unit watts
1
Whole-House LED Lighting (15 Fixtures)
150 Unit watts150 Unit watts
1
Fiber Internet ONT & Mesh WiFi Router
45 Unit watts45 Unit watts
1
Medical CPAP Machine (Heated Humidifier)
120 Unit watts120 Unit watts
1
Countertop Microwave Oven (1000W Cooking)
1,500 Unit watts1,500 Unit watts
1
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800 Unit feet

Lbl elevation derate note

75 Unit fahrenheit

Lbl temp derate note

Lbl fuel derate note

Lbl soft starter

Lbl soft starter desc

0.80

Lbl power factor desc

Title dual gauge

Lbl continuous running watts1,945Unit watts
Lbl peak starting surge watts3,295Unit watts
Lbl min generator continuous2,494Lbl nec headroom note
Lbl effective derate97.5%Status safe
80% NEC0%100%1,945 Unit watts36.3Unit percent Lbl continuous utilizationLbl surge: 3,295 Unit watts (49.2Unit percent)
Headroom safe msg
Lbl existing generatorLbl effective derate: 5,361Unit watts / 6,701Unit watts
Title waterfall1,945 Unit watts
Title soft start comparisonLbl surge reduction
Lbl without soft start2,150 Unit watts
Lbl with soft start1,232 Unit watts
Stat active count6
Lbl continuous running watts1,945 Unit watts
Lbl peak starting surge watts3,295 Unit watts
Lbl min generator continuous2,494 Unit watts
Lbl apparent power kva2.4 Unit kva
Stat reserve margin3,416 Unit watts