Marine Generator Sizing Calculator
Marine Generator Sizing
Size your marine generator based on onboard electrical loads including air conditioning, appliances, and electronics to ensure adequate power output.
Formula
Total Load = AC + Water Heater + Appliances + Electronics + Battery Charger; With Safety Margin = Total Load x (1 + Safety Margin %); Generator Size (kW) = Total Load with Margin / 1000
Frequently Asked Questions
How do I size a marine generator?
Add up the wattage of all electrical loads that may run simultaneously, then add a 20 to 25 percent safety margin. Generator size is rated in kilowatts, so divide the total watts by 1,000.
Can a generator run air conditioning on a boat?
Yes, but air conditioning is typically the largest load on a boat. A single 12,000 BTU marine AC unit draws about 1,200 to 1,500 watts. Most boats with AC need a generator of 5 kW or larger.
How much fuel does a marine generator use?
Marine generators typically consume 0.06 to 0.1 gallons per kilowatt hour. A 6 kW generator running at 50 percent load uses roughly 0.25 to 0.3 gallons per hour.
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