Watts A Amperes Calculator
Convert electrical power in watts to current in amperes using voltage and power factor.
Published by:
isCalculator Editorial Team
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How to use this tool?
This calculator converts Watts (W) to Amperes (A) using the formula: I = P / (V × PF) for single-phase, or I = P / (√3 × V × PF) for three-phase.
- Enter Power (Watts): Input the total power consumption (e.g., 1500). Must be a positive number.
- Enter Voltage (Volts): Input the system voltage (e.g., 120 for US household). Must be a positive number.
- Set Power Factor (0 to 1): Default is 1 (purely resistive loads). For inductive loads (motors), use a value like 0.8–0.9.
- Select Phase: Choose Single-Phase or Three-Phase.
- Click “Calculate”: The result appears in Amperes (A) below.
Note: All values must be positive. The power factor must be between 0 and 1. Use the same unit system (metric or imperial) consistently—voltage and power are unit-agnostic.
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Frequently Asked Questions
For single-phase: I = P / (V × PF). For three-phase: I = P / (√3 × V × PF), where P is power in watts, V is voltage in volts, and PF is power factor.
Power factor is a number between 0 and 1 that represents the ratio of real power to apparent power in an AC circuit. For purely resistive loads, it is 1.
Yes, for DC circuits, set power factor to 1 and select single-phase. The formula becomes I = P / V.