Electricity & Energy Calculators
Run-cost, appliance, and solar math in plain dollars — what a device costs, what a system makes, and your bill line by line.
32 free calculators · updated June 2026
Electricity Cost Calculator
What any device costs to run — watts, hours, and your rate to dollars per day, month, or year.
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Appliance Energy Use Calculator
See what each appliance adds to your bill — pick a common preset or enter your own watts.
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kWh to Watts Calculator
Turn kilowatt-hours and a time span into average watts — the power-versus-energy conversion.
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Watts to Amps Calculator
Amps from watts and volts — the breaker-and-wire-sizing question, with the 80% circuit rule.
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Amps to Watts Calculator
Watts from amps and volts — what a circuit or outlet can actually power, safely.
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Solar Panel Output Calculator
Estimate daily, monthly, and yearly production from system size, sun hours, and losses.
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Solar Panel Count Calculator
How many panels to cover your usage — by monthly kWh, sun hours, and panel wattage.
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Energy Bill Estimator
Build your monthly bill from usage, rate, fixed charges, and tax — and the true all-in $/kWh.
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kWh to Amps Calculator
Energy and a time span to average current — the two-step kWh → watts → amps conversion.
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Volts to Watts Calculator
Watts from volts and amps — for battery, automotive 12 V, and solar-string systems where voltage is known.
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Watts to Volts Calculator
Back out an unknown supply voltage from a measured load — the third leg of the W = V × A triangle.
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Battery Life Calculator
Runtime from capacity, load, and usable depth of discharge — lead-acid 50%, lithium 80%.
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Battery Watt-Hours Calculator
Amp-hours × volts to watt-hours — the only fair way to compare batteries of different voltages.
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Generator Size Calculator
The right generator wattage — running watts plus one starting surge, with 20% headroom.
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EV Charging Cost Calculator
What it costs to charge — battery size, the 20–80% window, your rate, and charging losses.
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Heating Cost Calculator
What electric heating costs to run — and why every 1,500 W resistance heater costs the same.
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Solar Battery Bank Size Calculator
Size an off-grid or backup battery bank — usage, days of autonomy, voltage, and usable depth.
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Watt to kWh Calculator
Turn watts and hours into kilowatt-hours — the building block behind every cost calc.
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Energy Savings Calculator
Dollars saved by replacing a device with an efficient one — annual, monthly, and kWh.
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LED Savings Calculator
What a whole-house switch to LED bulbs saves — by bulb count, wattage, and hours.
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Power Factor Calculator
Power factor and reactive power from real watts and apparent VA — the power triangle.
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Voltage Drop Calculator
Voltage lost over a wire run — current, distance, gauge, with the 3%/5% verdict.
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Electricity Usage Calculator
How much energy a device uses — watts, hours, and days to kWh, no dollars.
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Cost Per kWh Calculator
Your true all-in electricity rate — divide a bill total by the kWh used.
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Heat Pump Savings Calculator
What a heat pump saves vs resistance heat — the COP cuts the electricity to a fraction.
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Natural Gas Cost Calculator
Estimate a gas bill from therms and your rate — with the true all-in cost per therm.
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Gas vs Electric Heating Calculator
Which is cheaper to heat with — same useful heat, gas furnace vs heat pump or resistance.
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Water Heating Cost Calculator
What it costs to heat your hot water — gallons, temperature rise, and resistance vs heat pump.
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Phantom Load Calculator
What standby (vampire) power costs a year — devices, watts idle, and your rate.
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kWh to BTU Calculator
Convert kilowatt-hours to BTU — bridge the electric and heating/cooling worlds.
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BTU to kWh Calculator
Convert BTU to kilowatt-hours — turn a heat-energy figure into the energy your meter counts.
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Demand Charge Calculator
A commercial bill — a per-kW demand charge on your peak plus per-kWh energy, with the demand share.
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