Kilowatt Calculator

A kilowatt (kW) is an SI unit of electrical and mechanical power equal to 1,000 watts or approximately 1.341 mechanical horsepower. Unlike energy calc

Electrical

Calculation Method

Derive power from electrical parameters or convert power units

Voltage (Volts) or Value to Convert

V or units

Supply voltage if electrical; power value if converting

Current (Amperes)

Used in electrical mode

Power Factor (PF)

1.0 for resistive; 0.8 for AC motors

Circuit Phase

Single-phase or three-phase line-to-line

Formula & Methodology

Single-Phase: Power (kW) = (V × I × PF) ÷ 1000; Three-Phase: Power (kW) = (√3 × V × I × PF) ÷ 1000; Horsepower (HP) = Watts ÷ 745.7

To derive kilowatts from electrical parameters, multiply voltage by current and power factor, apply the phase multiplier (1.0 for single-phase, √3 for three-phase), and divide by 1,000. To convert between electrical power and mechanical motor power, divide watts by 745.7 to determine mechanical horsepower (or multiply horsepower by 0.7457 to determine kilowatts).

Calculated Electric Power (Kilowatts)

4.80 kW Power (kW)

Overview

A kilowatt (kW) is an SI unit of electrical and mechanical power equal to 1,000 watts or approximately 1.341 mechanical horsepower. Unlike energy calculators that evaluate kilowatt-hours over time, this Kilowatt Calculator focuses strictly on instantaneous power capacity: sizing electric generators, evaluating nameplate equipment specifications, and converting between electrical kilowatts and mechanical horsepower.

Power vs Energy Note: A kilowatt (kW) measures the instantaneous rate at which an electrical machine draws energy, whereas a kilowatt-hour (kWh) measures total energy consumed over time. A 4.8 kW electric vehicle charger operating at full load continuously draws 4.8 kW of electrical power.

Worked Examples

240V 20A Electric Dryer Circuit (PF = 1.0)

Voltage = 240 V, Current = 20 A, PF = 1.0, Single-phase.

Calculate Real Watts: 240 V × 20 A × 1.0 = 4,800 W
Convert to Kilowatts: 4,800 W ÷ 1,000 = 4.80 kW
Convert to Mechanical Horsepower: 4,800 W ÷ 745.7 = 6.44 HP
Convert to Megawatts: 4.80 kW ÷ 1,000 = 0.0048 MW

Final Answer: 4.80 kW (4,800 W | 6.44 HP | 0.0048 MW)

Three-Phase 480V 50A Industrial Line (PF = 0.85)

Voltage = 480 V, Current = 50 A, Three-phase, PF = 0.85.

Apply Formula: (√3 × 480 V × 50 A × 0.85) ÷ 1,000
Compute: (1.732 × 480 × 50 × 0.85) ÷ 1,000 = 35,334 W ÷ 1,000 = 35.33 kW
Convert to Horsepower: 35,334 ÷ 745.7 = 47.38 HP

Final Answer: 35.33 kW (47.38 HP)

Convert 2 kW directly to Other Power Units

Power = 2.0 kW.

Watts: 2.0 kW × 1,000 = 2,000 W
Horsepower: 2,000 ÷ 745.7 = 2.68 HP
Megawatts: 2.0 ÷ 1,000 = 0.002 MW

Final Answer: 2.00 kW (2,000 W | 2.68 HP | 0.002 MW)

How to Use This Calculator

Select whether you want to calculate kW from voltage and amperage, or convert existing power units.

Enter the voltage and current, or enter the power value you wish to convert.

Select single-phase or three-phase power.

Enter the equipment power factor (default 1.0 for heating, 0.85 for motors).

Click Calculate to see power in Kilowatts, Watts, Horsepower, and Megawatts.

Reference Table

Power Unit	Abbreviation	Equivalent in Watts	Equivalent in Kilowatts
Watt	W	1 W	0.001 kW
Kilowatt	kW	1,000 W	1.0 kW
Mechanical Horsepower	HP	745.7 W	0.7457 kW
Metric Horsepower	PS / CV	735.5 W	0.7355 kW
Megawatt	MW	1,000,000 W	1,000 kW
Gigawatt	GW	1,000,000,000 W	1,000,000 kW

Frequently Asked Questions

How do I convert amps and volts to kilowatts (kW)?

For single-phase power, multiply volts by amps and power factor, then divide by 1,000: kW = (V × I × PF) ÷ 1,000. For example, 240V × 20A × 1.0 = 4,800 watts = 4.8 kW.

What is the conversion between horsepower and kilowatts?

One mechanical horsepower (HP) equals approximately 745.7 watts or 0.7457 kW. Conversely, 1 kW equals approximately 1.341 horsepower (HP = kW × 1.341).

Why does generator sizing use kilowatts instead of kilowatt-hours?

Generators are rated in kilowatts (kW) or kilovolt-amperes (kVA) because they must supply the peak instantaneous electrical demand of connected loads at any given moment, regardless of how long those loads operate.

How many kilowatts is a 200-amp residential electric service?

A standard 200-amp 240-volt residential service panel has a maximum continuous capacity of (240 V × 200 A) ÷ 1,000 = 48.0 kW.

Is a kilowatt equal to a kilowatt-hour?

No. A kilowatt (kW) measures power—the rate of energy use at an instant. A kilowatt-hour (kWh) measures total energy consumed over time. A 2 kW motor running for 1 hour consumes 2 kWh.