GridComfort

Calculators

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Free calculators, each built on a published table rather than a rule of thumb. The generator wattage calculator adds up running watts and the largest starting surge from manufacturers' wattage charts and suggests a generator class. The generator fuel calculator works out how long a tank lasts, or how much fuel a planned run needs, from the run times the manufacturers publish. The BTU calculator sizes a room air conditioner from the ENERGY STAR table and its adjustments for sun, people and kitchens. The dehumidifier calculator gives pints per day under the 2019 rating and maps them to the sizes sold in stores. The electricity cost calculator turns an appliance's watts and daily hours into cost per day, month and year at EIA's average residential rate for your state.

Each calculator has a methodology page listing its data source, formula and limits, so any result can be checked by hand. They give estimates. For a real installation, the appliance's nameplate and an electrician's load calculation take precedence.

CalculatorGenerator Wattage CalculatorRunning watts, the largest starting surge, and a generator class from manufacturer charts.CalculatorGenerator Fuel CalculatorRunning time from the fuel you have, or fuel and cost for a planned run, from published tank and run-time figures.CalculatorAir Conditioner BTU CalculatorThe ENERGY STAR sizing table with its sun, people, and kitchen adjustments.CalculatorDehumidifier Sizing CalculatorPints per day under the 2019 rating, mapped to the sizes stores sell.CalculatorAppliance Electricity Cost CalculatorCost per day, month, and year at your state’s average rate (EIA).

Methodology pages