Electrical Calculators
Free electrical calculators for power, current, voltage, power factor, energy, batteries, voltage drop, wire gauge and lighting, with every formula shown.
Power & Energy
- Electrical Power CalculatorFind real power, current or voltage for a DC, single-phase or three-phase circuit, and see apparent power, reactive power and phase angle from the power factor.
- Power Factor CalculatorWork out a load's power factor and phase angle, and size the power factor correction capacitors needed to reach a target such as 0.95.
- Electrical Energy CalculatorRelate energy, power and time (kW to kWh, joules to watts) and energy, charge and voltage (joules or electronvolts to volts), with every step shown.
- Battery Capacity CalculatorConvert between milliamp-hours and watt-hours at a battery's nominal voltage and estimate runtime for a load, including a usable-capacity allowance.
- Electricity Cost CalculatorEstimate appliance energy and cost using watts, daily running hours, days, duty fraction and your electricity unit price.
Wiring
- Voltage Drop CalculatorEstimate how much voltage a cable loses between the supply and the load, as volts and as a percentage, for copper or aluminum conductors.
- Wire Gauge CalculatorLook up any AWG or SWG gauge's diameter, cross-sectional area and resistance, or find the nearest gauge for a diameter or mm² size.
Circuits & Components
- Voltage Divider CalculatorCalculate a two-resistor divider’s output, input current and resistor dissipation, including an optional resistive output load.
- Resistor Color Code CalculatorRead 4-, 5- or 6-band resistor colors as ohms with tolerance and ppm/K drift, or enter a resistance to get its bands and the nearest standard E-series value.
- Capacitor Energy CalculatorCalculate ideal stored energy and charge magnitude from capacitance in microfarads and capacitor voltage.
- Ohm’s Law CalculatorEnter any two of voltage, current, resistance and power to solve the other two for an ideal resistor, with the working shown.