Electrical calculators
Watts, amps and volts, kWh, Ohm’s law and wire gauge sizing. Every tool below is free, works instantly in your browser and explains the formula behind the result.
Electrical calculations decide whether an appliance can share a circuit, what breaker a load needs and which wire gauge is safe for a run. These tools convert between watts, amps and volts for DC and single- or three-phase AC, apply Ohm’s law, turn power into kilowatt-hours and cost, and estimate wire size from ampacity and voltage drop. They are planning aids — electrical work should follow local codes.
8 tools in this category
- Watts to Amps CalculatorFind how many amps an appliance or circuit draws from its wattage and voltage.
- Amps to Watts CalculatorConvert current in amps to power in watts at any voltage — for example, to see how much load a 15 A or 20 A circuit can carry.
- Volts to Watts CalculatorVolts alone do not tell you watts — you also need the current or the resistance.
- kWh CalculatorWork out how many kilowatt-hours a device uses, or the average power behind a kWh figure, and what that energy costs.
- Ohm’s Law CalculatorEnter any two of voltage (V), current (I), resistance (R) and power (P), and the calculator works out the other two.
- Wire Gauge CalculatorEstimate the wire gauge (AWG) needed for a circuit.
- AWG to mm² ConverterConvert wire sizes between American Wire Gauge (AWG) and metric cross-sectional area in mm², with diameter and the nearest standard metric size.
- kVA to kW ConverterConvert apparent power (kVA) to real power (kW) or back, using the power factor of the load.
Other categories
- Temperature converters
- Time & date calculators
- Math & number converters
- Weather calculators
- Cooking & kitchen converters
- Length & height converters
- Weight converters
- Volume & liquid converters
- Data & digital converters
- Speed, area & engineering converters
- Home energy & HVAC calculators
- Home improvement calculators
- Tech & auto temperature guides
- Size converters
- Everyday calculators