How Many Amps Is 1 kW?
1 kW is 8.33 A at 120 V DC. At other common voltages — 240 V: 4.17 A. Use the calculator below for any voltage or circuit type.
1 kW to Amps — Reference Chart
| Circuit | Voltage | PF | Amps |
|---|---|---|---|
| DC | 120 V | — | 8.3333 A |
| DC | 240 V | — | 4.1667 A |
| DC | 480 V | — | 2.0833 A |
| AC 1Ø | 120 V | 1.0 | 8.3333 A |
| AC 1Ø | 120 V | 0.8 | 10.4167 A |
| AC 1Ø | 240 V | 1.0 | 4.1667 A |
| AC 1Ø | 240 V | 0.8 | 5.2083 A |
| AC 3Ø (L-L) | 208 V | 0.8 | 3.4693 A |
| AC 3Ø (L-L) | 480 V | 0.8 | 1.5026 A |
Breaker sizing tip: 1 kW at 120 V draws 8.33 A. Per NEC 210.20, continuous loads require breakers sized at 125%: 8.33 × 1.25 = 10.42 A. A standard 15 A breaker is the correct choice. At 240 V (4.17 A), a 15 A breaker is also adequate. Always consult a licensed electrician.
In practice: a 1 kW immersion element
One kilowatt draws 8.3 A at 120 V or 4.35 A on a 230 V supply — the rating of a small immersion heater or a compact oil-filled radiator. Almost any existing circuit copes at this level, and cable size is rarely the limiting factor. What is worth checking is what shares the circuit, because 1 kW already consumes over half a 15 A budget once continuous derating applies.
Frequently Asked Questions
How many amps is 1 kW at 120V?
1 kW at 120 V DC = (1 × 1,000) ÷ 120 = 8.3333 amps. For AC single-phase with PF 0.8: (1,000) ÷ (120 × 0.8) = 10.4167 amps.
How many amps is 1 kW at 240V?
1 kW at 240 V DC = (1 × 1,000) ÷ 240 = 4.1667 amps. For AC single-phase with PF 0.8: (1,000) ÷ (240 × 0.8) = 5.2083 amps.
What size breaker do I need for 1 kW?
At 120 V, 1 kW draws 8.33 A. The NEC requires breakers sized at 125% for continuous loads: 8.33 × 1.25 = 10.42 A. A standard 15 A breaker is sufficient. At 240 V (4.17 A), a 15 A breaker is also adequate. Always consult a licensed electrician.