Electrical Power Calculator | Watts, Volts, Amps & kWh Cost

The Power Triangle illustrates the relationship between Real Power (Watts), Reactive Power (VAR), and Apparent Power (VA). The angle between Real and Apparent power represents the Power Factor. A power factor of 1.0 means all power is usable real power.

For DC circuits: P = V × I (Voltage × Current). For single-phase AC: P = V × I × Power Factor. For 3-phase AC: P = √3 × V_line × I_line × PF. Select your circuit type in this calculator for the correct formula.

Energy (kWh) = Power (W) × Time (hours) / 1000. Cost = kWh × electricity rate. For example, a 1,500W heater running 8 hours at $0.12/kWh: 1.5 × 8 × $0.12 = $1.44/day. Use the kWh Cost mode in this calculator to project daily, monthly, and annual costs.

Power factor (PF) is the ratio of real power (W) to apparent power (VA). PF = 1.0 is ideal (purely resistive load). Motors, transformers, and fluorescent lights typically have PF of 0.7-0.95. A low PF means you draw more current for the same usable power, increasing losses and utility bills.

Yes! In guest mode, you can export your calculations to JSON format. Sign in is required for PDF and CSV export. Click the export button to download your results. This is perfect for record-keeping, sharing with others, or importing into other tools.

Yes! Your calculation history is automatically saved. Guest users can save up to 50 calculations per workspace locally. Sign in for free to save up to 100 calculations per workspace, with access from any device when logged in.

Absolutely! The Power Calculator is completely free with no sign-up required. Create a free account to unlock additional features like more calculation history, multiple workspaces, and the ability to access your saved data from any device.