Amps to kW Calculator
Convert amperes to kilowatts for any voltage. Enter the current in amps and voltage to calculate power in kW. Works for 120V, 240V, and three-phase systems.
How to Convert Amps to kW
The formula to convert amps to kilowatts is: kW = (Amps × Volts) ÷ 1000.This comes from the power equation P = V × I, then dividing by 1,000 to convert watts to kilowatts. Kilowatts are the standard unit for measuring electrical power consumption of larger loads.
Single-phase: kW = (A × V) ÷ 1000
Three-phase: kW = (A × V × √3) ÷ 1000
For example, a 30-amp circuit at 240 volts delivers 7.2 kW (30 × 240 ÷ 1000). Understanding the kW rating helps you estimate energy costs — a 7.2 kW load running for one hour uses 7.2 kWh, which at $0.15/kWh costs about $1.08.
For three-phase circuits, multiply by √3 (1.732) because power is distributed across three conductors. A 50-amp, 480V three-phase circuit delivers 41.57 kW — far more than the 24 kW you'd get from 50 amps at 480V single-phase. Use our three-phase power calculator for more complex three-phase calculations.
Amps to kW Conversion Chart
| Amps | @ 120V | @ 240V | @ 480V (3Φ) |
|---|---|---|---|
| 5 A | 0.60 kW | 1.20 kW | 4.16 kW |
| 10 A | 1.20 kW | 2.40 kW | 8.31 kW |
| 15 A | 1.80 kW | 3.60 kW | 12.47 kW |
| 20 A | 2.40 kW | 4.80 kW | 16.63 kW |
| 30 A | 3.60 kW | 7.20 kW | 24.94 kW |
| 40 A | 4.80 kW | 9.60 kW | 33.25 kW |
| 50 A | 6.00 kW | 12.00 kW | 41.57 kW |
| 60 A | 7.20 kW | 14.40 kW | 49.88 kW |
| 80 A | 9.60 kW | 19.20 kW | 66.51 kW |
| 100 A | 12.00 kW | 24.00 kW | 83.14 kW |
| 150 A | 18.00 kW | 36.00 kW | 124.70 kW |
| 200 A | 24.00 kW | 48.00 kW | 166.27 kW |
| 400 A | 48.00 kW | 96.00 kW | 332.54 kW |
Frequently Asked Questions
How do you convert amps to kW?
Multiply amps by volts, then divide by 1,000 to get kilowatts. The formula is: kW = (Amps × Volts) ÷ 1000. For example, 30 amps at 240 volts equals 7.2 kW (30 × 240 ÷ 1000 = 7.2). For three-phase circuits, multiply by √3 (1.732): kW = (Amps × Volts × 1.732) ÷ 1000.
How many kW is 100 amps at 240V?
100 amps at 240 volts equals 24 kW (100 × 240 ÷ 1000 = 24). This is the capacity of a typical 100-amp sub-panel or a large electrical service. A 200-amp residential service at 240V provides 48 kW of total capacity.
How many kW is 20 amps at 120V?
20 amps at 120 volts equals 2.4 kW (20 × 120 ÷ 1000 = 2.4). This is the maximum capacity of a standard 20-amp household circuit. With the NEC 80% rule for continuous loads, the usable capacity is 1.92 kW.
How do I convert amps to kW for three-phase?
For three-phase circuits, use: kW = (Amps × Volts × √3) ÷ 1000. For example, 50 amps at 480V three-phase equals 41.57 kW (50 × 480 × 1.732 ÷ 1000 = 41.57). The √3 factor accounts for the power delivered across all three phases.
How many kW is 50 amps at 240V?
50 amps at 240 volts single-phase equals 12 kW (50 × 240 ÷ 1000 = 12). This is the capacity of a typical electric range or large EV charger circuit. At 480V three-phase, 50 amps provides 41.57 kW.
What is the difference between kW and kVA?
kW (kilowatts) measures real power — the actual power doing useful work. kVA (kilovolt-amperes) measures apparent power, which includes both real power and reactive power. The relationship is: kW = kVA × Power Factor. For resistive loads (heaters, incandescent lights), power factor is ~1.0 so kW ≈ kVA. For motors, power factor is typically 0.8–0.9.
How many kW does a 200-amp service provide?
A 200-amp service at 240V single-phase provides 48 kW (200 × 240 ÷ 1000 = 48). This is the standard residential electrical service in the US. However, you never use 100% of the service capacity — the NEC demand factor calculations typically result in using 60–80% of the total capacity.
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