kW to Amps Calculator
Convert kilowatts to amps for single-phase and 3-phase AC systems. Calculate circuit current from real power, voltage, and power factor for electrical planning.
Amps (1-phase)
15.625 A
3-phase equivalent: 9.0211 A
Current (A)
15.625
Voltage (V)
120
Power (W)
1500
Power (kW)
1.5
Formula Used
A = (kW × 1000) / (V × PF) = (1.5 × 1000) / (120 × 0.8)
A = (kW × 1000) / (V × PF)
About the kW to Amps Calculator
A kW to amps calculator converts real power in kilowatts to current in amperes for single-phase and three-phase AC circuits, accounting for the circuit voltage and power factor. This is one of the most practically important electrical calculations: you know how much power a device consumes (from its nameplate or energy meter), and you need to know how much current it draws to size the circuit breaker, wiring, and connection hardware correctly. Every electrical installation standard — NEC in the USA, BS 7671 in the UK, AS/NZS 3000 in Australia — requires knowing the Full Load Current (FLC) to properly size overcurrent protection and conductors. Our free kW to amps calculator handles residential 120V and 240V single-phase (US), 230V single-phase (EU/UK/AU), 208V and 480V three-phase (US commercial/industrial), and 400/415V three-phase (EU/AU). It includes voltage quick-select buttons for the most common system voltages and shows both single-phase and three-phase results simultaneously for comparison.
Formula
Single-phase: A = (kW × 1000) / (V × PF) | 3-phase: A = (kW × 1000) / (V × PF × √3) | Breaker: FLC × 1.25
How It Works
Single-phase: A = (kW × 1000) / (V × PF). Three-phase: A = (kW × 1000) / (V × PF × √3). Example 1 (US residential): 5 kW electric range at 240V, PF 1.0: A = (5 × 1000) / (240 × 1.0) = 20.83A. Round up for breaker: 25A or 30A depending on code. Example 2 (commercial HVAC): 7.5 kW air handler motor at 208V 3-phase, PF 0.85: A = (7,500) / (208 × 0.85 × 1.732) = 7,500 / 306.5 = 24.5A. 125% for continuous: 30.6A → 35A breaker. Example 3 (industrial pump): 22 kW pump at 480V 3-phase, PF 0.88: A = (22,000) / (480 × 0.88 × 1.732) = 22,000 / 732.2 = 30.0A. Breaker: 37.5A → 40A.
Tips & Best Practices
- ✓The NEC 125% continuous load rule applies when equipment operates for 3+ consecutive hours. Multiply calculated amps by 1.25 before selecting a breaker. Short-duration loads (microwave, toaster, power tools) do not require the 125% adder.
- ✓Motor Full Load Current (FLC): NEC Table 430.248 (single-phase) and 430.250 (3-phase) list standard FLC values for motors at specific voltages and horsepower ratings. Always use these NEC table values, not nameplate amps alone, when sizing motor branch circuit components.
- ✓EV Level 2 charging: 7.2 kW at 240V = 30A; 9.6 kW = 40A; 11.5 kW = 48A; 19.2 kW = 80A. EVSE (charging station) circuits require 125% overcurrent protection since EV charging is a continuous load: 48A × 1.25 = 60A breaker minimum.
- ✓3-phase motor horsepower to amps: 1 HP = 0.746 kW. A 15 HP motor = 11.19 kW. At 460V 3-phase with 0.88 PF: A = 11,190 / (460 × 0.88 × 1.732) = 15.9A. NEC Table 430.250 lists 21A for a 15 HP, 460V motor — using the table value provides the code-required sizing basis.
Who Uses This Calculator
Electricians sizing circuit breakers and conductors for new equipment installations. Engineers performing load calculations for panel boards and service entrance sizing. Homeowners planning EV charger installations who need to know the required circuit amperage. Facilities managers adding new equipment and verifying existing circuit capacity. Anyone specifying backup generators and needing to convert load kW to amps for transfer switch sizing.
Optimised for: USA · UK · Canada · Australia · Calculations run in your browser · No data stored
Frequently Asked Questions
How do I convert kW to amps?
Single-phase: A = (kW × 1000) / (V × PF). Three-phase: A = (kW × 1000) / (V × PF × √3). Example: 5 kW at 240V, PF 0.85 single-phase: A = 5,000 / (240 × 0.85) = 24.5 amps.
How many amps does a 3 kW heater draw?
At 120V (US): A = 3,000 / 120 = 25A (PF ≈ 1 for resistive heaters). At 240V (US): A = 3,000 / 240 = 12.5A. At 230V (EU): A = 3,000 / 230 = 13A. Heating elements are resistive — PF = 1 exactly.
What wire size do I need for a 7.2 kW electric vehicle charger?
At 240V, PF ≈ 1: A = 7,200 / 240 = 30A. NEC requires 125% for continuous loads: 30 × 1.25 = 37.5A. Use 8 AWG copper wire with a 40A breaker. Most Level 2 EV charger installations use 40A circuits.
How many amps is a 10 kW solar inverter?
At 240V single-phase: A = 10,000 / 240 = 41.7A. At 208V 3-phase: A = 10,000 / (208 × 1.732 × 0.99) = 28.2A (PF ≈ 0.99 for quality inverters). Multiply by 1.25 for breaker sizing: 52A → 60A breaker.