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Amps to kW Calculator

Convert amps to kilowatts, or kW back to amps, for DC, single-phase, and three-phase circuits. WattSimple also shows the apparent power in kVA, how much of a standard NEC breaker the current occupies, and what the load costs to run at your state's electricity rate.

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What that load costs to run

Power

9.6 kW

Current
40 A
Real power
9.6 kW
Apparent power
9.6 kVA
Energy per month
1,167 kWh
Cost per month
$198.45

Breaker headroom

40 A is 100% of the next standard 40 A breaker (NEC 240.6). That exceeds the 80% ceiling for a continuous load: a load running 3 hours or more needs the next size up.

Code minimum only. Confirm conductor sizing, termination temperature, and derating with a licensed electrician and your local AHJ.

Measure the real amps and volts

The converter works from nameplate or assumed figures. A clamp meter reads the actual current on one conductor without breaking the circuit; clamped around a whole cord it reads close to zero. A multimeter reads the voltage at the receptacle or terminals. Opening a panel or a live box is work for someone qualified.

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Frequently asked questions

Multiply amps by volts, multiply by power factor on AC, then divide by 1,000. Single-phase: kW = A × V × PF ÷ 1,000. Three-phase: kW = 1.732 × A × V × PF ÷ 1,000. Example: 40 A at 240 V single-phase at unity power factor = 9.6 kW.

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Sources & standards

This tool's methodology and data follow US standards and authoritative public datasets: