Energy Calculators
Find what an appliance costs to run, how long a battery lasts, or how big a solar system you need. For electronics, there are calculators for Ohm’s law, LED and resistor networks, voltage dividers and RC time constants.
Browse calculators
18 toolsAC Current Calculator
Estimate single-phase or balanced three-phase current from real power, apparent power or motor output.
Open calculatorAppliance Electricity Cost Calculator
Estimate electricity costs from appliance power and usage or measured daily, weekly or monthly kWh.
Open calculatorBattery Charge Time Calculator
Estimate charging time or the modelled current needed for a time budget, with an optional entered taper allowance.
Open calculatorBattery Runtime Calculator
Estimate battery runtime from capacity and a total watt load, load-side current or an editable device list.
Open calculatorCapacitor Energy Calculator
Calculate ideal capacitor energy, solve voltage or capacitance, and estimate energy released above a cutoff.
Open calculatorEV Charging Calculator
Estimate EV charging to a target or within available hours, including energy, per-minute and session charges.
Open calculatorHeat Pump Cost Calculator
Estimate heat-pump electricity and running cost from heat energy or output hours, and compare resistance or fuel heating.
Open calculatorLED Resistor Calculator
Choose an E12 or E24 LED resistor or check an existing value, with per-string current, power and repeated-string totals.
Open calculatorOhm’s Law Calculator
Solve voltage, current, resistance and DC power from any two known quantities with selectable electrical units.
Open calculatorParallel Resistor Calculator
Add or paste up to 100 parallel or series resistors, with retained unit conversion, component loading and tolerance limits.
Open calculatorPower Factor Calculator
Find power factor from P/S, a sinusoidal power triangle or real power with single-phase or balanced three-phase RMS measurements.
Open calculatorRC Time Constant Calculator
Calculate RC voltage after a time or time to a transition target, with selectable units and nonzero voltage endpoints.
Open calculatorSeries Resistor Calculator
Add or paste series resistors and calculate equivalent resistance, individual loading and source voltage or current.
Open calculatorSolar Energy Calculator
Estimate solar generation from array capacity or panel count, with entered self-use energy and separate import/export prices.
Open calculatorSolar Payback Calculator
Compare constant solar payback with yearly generation, tariff, upkeep and replacement assumptions in an undiscounted cash-flow table.
Open calculatorSolar System Size Calculator
Size solar capacity and whole panels from daily or billing-period electricity use, with an optional entered panel-area comparison.
Open calculatorVoltage Divider Calculator
Calculate loaded divider voltage or solve either resistor for a target, with retained units and fixed-load tolerance bounds.
Open calculatorWire Resistance Calculator
Estimate copper or aluminum DC wire resistance with retained length, area and temperature units plus optional source-voltage loss comparison.
Open calculatorNo calculators match that search.
Try a topic such as percentages, savings, or dates.