Amps to kW Calculator
Convert a current (amps) and voltage reading into real power in kilowatts, for both single-phase and three-phase circuits.
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The single-phase result applies to standard residential/single-phase circuits. The three-phase result applies to three-phase industrial/commercial circuits — use whichever matches your actual system. Related resources: [How to Convert Amps to Kilowatts](/guides/how-to-convert-amps-to-kilowatts), [Watts to Amps Calculator](/watts-to-amps-calculator), [3 Phase Power Calculator](/3-phase-power-calculator), [Electrical Load Calculator](/electrical-load-calculator).
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How to Convert Amps to Kilowatts
Electrical power in kilowatts depends on both current (amps) and voltage — you can't convert amps to power without knowing the voltage of the circuit.
How to Calculate Kilowatts from Amps
Kilowatts = (Amps × Volts) ÷ 1,000 for a standard single-phase DC or resistive AC circuit.
Amps to kW Calculator Formula
- Watts = Amps × Volts
- Kilowatts = Watts ÷ 1,000
Why Do I Need Voltage to Convert Amps?
Because power (watts) is the product of current and voltage — the same amperage at a higher voltage delivers more power. This is why household voltage (120V or 240V depending on region and circuit) meaningfully changes the kilowatt result for the same amp reading.
Amps to kW Examples
240V circuit, 20A: (20 × 240) ÷ 1,000 = 4.8 kW.
Common Amps-to-kW Conversion Mistakes
Converting without accounting for voltage, which is required for any amps-to-power conversion. Using this simplified formula for three-phase power, which requires an additional factor (√3 for line-to-line voltage) not included in this single-phase calculation. Confusing kilowatts (real power) with kilovolt-amps (apparent power) — they're equal for purely resistive loads but differ when reactive power (from motors, capacitors) is involved.
How to Use This Calculator
Enter the current in amps, the voltage, and the power factor (use 1.0 if unknown for a purely resistive load).
Formula & Methodology
Single-phase: kW = (Amps × Volts × Power Factor) / 1000. Three-phase: kW = (Amps × Volts × Power Factor × √3) / 1000, where √3 ≈ 1.732.
Example: 20A at 240V, power factor 1.0
Single-phase: (20 × 240 × 1.0) / 1000 = 4.8 kW. Three-phase: (20 × 240 × 1.0 × 1.732) / 1000 ≈ 8.31 kW.
Power factor defaults to 1.0 (purely resistive). Real motor and inductive loads typically have a power factor below 1.0 — use the load's actual rated power factor for an accurate result.
For estimation purposes only. Electrical work should be verified and performed by a licensed electrician.
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Related Guides
- How to Convert Amps to Kilowatts: Single-Phase and Three-Phase FormulasConvert amps to kilowatts using the correct formula for single-phase or three-phase circuits. Covers power factor, worked examples, and a quick reference table.
- How Three-Phase Power Is Calculated: Watts, Amps, and Power FactorUnderstand three-phase power calculations — how to find real power (kW), apparent power (kVA), reactive power (kVAR), and current from three-phase motor and generator specifications.
- How to Use the Air Conditioning Installation Cost CalculatorLearn how to use the Air Conditioning Installation Cost Calculator, check its formula and interpret the result.
- How to Use the Furnace and AC Replacement Cost CalculatorLearn how to use the Furnace and AC Replacement Cost Calculator, check its formula and interpret the result.
- How to Convert Watts to Amps: Single-Phase and DC FormulasLearn how to convert watts to amps using Ohm's Law and power formulas for DC circuits, single-phase AC, and three-phase AC with practical worked examples.
Frequently Asked Questions
- How do you convert amps to kW?
- Multiply amps by volts and power factor, then divide by 1000 for single-phase. For three-phase, also multiply by the square root of 3 (about 1.732).
- What power factor should I use?
- Use 1.0 for purely resistive loads like heaters. For motors and other inductive loads, use the equipment's rated power factor, typically between 0.8 and 0.95.
- What's the difference between single-phase and three-phase results?
- They're different electrical systems — use the single-phase result for standard circuits and the three-phase result only if your system is actually wired three-phase.
Last updated 7/22/2026