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Amps to Watts Calculator

Convert electrical current (Amps) to power (Watts) for DC and AC Single-Phase circuits. Essential for sizing circuit breakers and power supplies.

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About

Electrical load calculation is the cornerstone of safe circuit design. Whether sizing a fuse for a DC automotive accessory or planning the load for a residential branch circuit, knowing the exact power consumption prevents thermal overload and fire hazards. This tool converts Current (I) to Power (P) by integrating Voltage (V) and, for Alternating Current, the Power Factor (PF). The Power Factor is critical in AC circuits; neglecting it when dealing with inductive loads like motors or transformers leads to underestimated power requirements and tripped breakers.

electrical power amps watts voltage calculator

Formulas

The relationship between current and power depends on the current type:

1. Direct Current (DC):

PW = IA × VV

2. AC Single-Phase:

PW = IA × VV × PF

Where P is Power in Watts, I is Current in Amps, V is Voltage in Volts, and PF is the Power Factor (dimensionless ratio 0 to 1).

Reference Data

Circuit TypeVoltage (V)Current (I)Power FactorResult (P)
DC (USB)52.1N/A10.5 W
DC (Automotive)1215N/A180 W
AC (US Std)120100.91080 W
AC (US Heavy)240301.07200 W
AC (EU Std)230160.853128 W
AC (Inductive)208500.88320 W
AC (Heater)11012.51.01375 W
DC (Truck)245N/A120 W

Frequently Asked Questions

In AC circuits, especially those with motors or compressors, the current and voltage waves may not align perfectly. The Power Factor represents this inefficiency. A Power Factor of 1.0 means 100% efficiency (resistive load like a heater), while 0.8 means only 80% of the current is doing useful work. Ignoring this can lead to undersized wiring.
Watts (W) measure real power-the actual work done. Volt-Amps (VA) measure apparent power. In DC circuits, they are identical. In AC circuits, Watts = VA × Power Factor.
This specific tool is designed for DC and AC Single-Phase. Three-phase calculations require a radical factor (square root of 3) which is not included in the standard single-phase formula used here.
You would reverse the formula: Amps = Watts / (Volts × PF). This tool is designed to calculate Watts from Amps, but the algebraic relationship holds in reverse.