First, sum the wattage of all loads you need to run simultaneously. Add the largest single starting surge (typically 3x to 6x running watts for motors). Divide this total peak wattage by the power factor — usually 0.8 for inductive loads — to get kVA. Finally, multiply by 1.2 to add the industry-standard 20% safety margin.

Both are critical, but starting watts often dictate the minimum generator size. Motors in air conditioners, refrigerators, well pumps, and compressors can draw several times their running wattage at startup. Your generator set must handle the highest single surge while your other continuous loads are already running.

Yes. An oversized generator running below 30% capacity operates inefficiently, wastes fuel, and can suffer from carbon buildup known as wet stacking in diesel engines. The optimal operating range is typically 50% to 80% of the rated capacity, which is why accurate sizing matters.

Fuel type can influence the effective output of your generator set. Natural gas has lower energy density than diesel or propane, so a natural gas generator may need to be sized slightly larger to deliver the same kW output. Fuel choice also impacts storage requirements, runtime, and ongoing maintenance schedules.

Your downloadable PDF report includes your total connected load, effective continuous load, largest starting surge, calculated kVA and kW requirements, applied safety margin, environmental derating factors, and recommended ZC Power generator set models with direct links to technical datasheets and quote requests.