kW to amps converter
Converting kW to amps turns a load's real power in kilowatts into the current it draws, using the supply voltage, the power factor and, for three-phase loads, the factor √3. Commercial heaters, EV chargers, electric boilers and process equipment are commonly rated in kilowatts rather than watts.
Convert kW to amps
Updates as the values change. The page address keeps the values for sharing.
Larger loads are often three phase, at 208 V or 480 V, and their data sheets may list either the line-to-line or the line-to-neutral voltage. The converter accepts both, so a 480Y/277 V or 208Y/120 V system can be entered the way it appears on the drawing.
Formulas
DC
Battery banks and DC fast-charging equipment rated in kilowatts convert directly: 10 kW on a 400 V DC bus is 25 A.
Single phase AC
Typical for residential equipment over a few kilowatts, such as EV chargers and electric furnaces at 240 V. Charger and heater nameplates usually show a power factor close to 1.
Three phase AC
Covers 208 V and 480 V commercial systems. With line-to-neutral entry the formula is the same as I = kW × 1,000 ÷ (3 × V(L-N) × PF).
The factor 1,000 converts kilowatts to watts. Line-to-line voltage is the voltage between two phase conductors (208 V or 480 V); line-to-neutral is phase to neutral (120 V or 277 V).
Worked examples
An 11.5 kW EV charger on a 240 V circuit
Level 2 chargers present a power factor close to 1.
P = 11.5 kW × 1,000 = 11,500 WI = P ÷ (V × PF)I = 11,500 W ÷ (240 V × 1) = 47.92 A
The charger draws 47.92 A. EV charging equipment is treated as a continuous load under NEC 625.41, so the branch circuit is sized above this current, not at it.
A 30 kW duct heater at 480 V three phase
An electric resistance heater, power factor 1, on a 480Y/277 V system entered line to line.
P = 30 kW × 1,000 = 30,000 WI = P ÷ (√3 × V(L-L) × PF)I = 30,000 W ÷ (1.732 × 480 V × 1) = 36.08 A
Each line carries 36.08 A. On a 208 V system the same heater would draw 83.27 A, which is why large heating loads are usually supplied at 480 V.
15 kW of mixed load on a 208Y/120 V panel, entered as 120 V line to neutral, PF 0.9
The drawing lists the system as 120 V to neutral. The converter multiplies by √3 to get the 208 V line-to-line value.
P = 15 kW × 1,000 = 15,000 WV(L-L) = √3 × V(L-N) = 1.732 × 120 V = 207.85 VI = P ÷ (√3 × V(L-L) × PF)I = 15,000 W ÷ (1.732 × 207.85 V × 0.9) = 46.3 A
Each line carries 46.30 A. Entering 120 V as if it were line to line would give 80.19 A, an overstatement by a factor of √3.
Conversion tables
| kW (kW) | 120 V single phase (A) | 240 V single phase (A) | 208 V three phase (A) | 480 V three phase (A) |
|---|---|---|---|---|
| 1 | 8.3 | 4.2 | 2.8 | 1.2 |
| 2 | 16.7 | 8.3 | 5.6 | 2.4 |
| 3 | 25.0 | 12.5 | 8.3 | 3.6 |
| 5 | 41.7 | 20.8 | 13.9 | 6.0 |
| 7.5 | 62.5 | 31.3 | 20.8 | 9.0 |
| 10 | 83.3 | 41.7 | 27.8 | 12.0 |
| 12 | 100.0 | 50.0 | 33.3 | 14.4 |
| 15 | 125.0 | 62.5 | 41.6 | 18.0 |
| 20 | 166.7 | 83.3 | 55.5 | 24.1 |
| 25 | 208.3 | 104.2 | 69.4 | 30.1 |
| 30 | 250.0 | 125.0 | 83.3 | 36.1 |
| 40 | 333.3 | 166.7 | 111.0 | 48.1 |
| 50 | 416.7 | 208.3 | 138.8 | 60.1 |
| 75 | 625.0 | 312.5 | 208.2 | 90.2 |
| 100 | 833.3 | 416.7 | 277.6 | 120.3 |
| kW (kW) | 208 V three phase, PF 0.8 (A) | 480 V three phase, PF 0.8 (A) |
|---|---|---|
| 5 | 17.3 | 7.5 |
| 10 | 34.7 | 15.0 |
| 15 | 52.0 | 22.6 |
| 20 | 69.4 | 30.1 |
| 25 | 86.7 | 37.6 |
| 30 | 104.1 | 45.1 |
| 40 | 138.8 | 60.1 |
| 50 | 173.5 | 75.2 |
| 75 | 260.2 | 112.8 |
| 100 | 347.0 | 150.4 |
| 150 | 520.4 | 225.5 |
| 200 | 693.9 | 300.7 |
Both tables come from the converter's engine. The PF 0.8 table illustrates the effect of power factor; actual loads use their own nameplate values.
Common mistakes
Forgetting the factor of 1,000
Dividing kilowatts directly by volts gives an answer a thousand times too small. Kilowatts are converted to watts first, or the result is read as kiloamperes.
Entering 277 V or 120 V as a line-to-line voltage
277 V and 120 V are line-to-neutral voltages of 480Y/277 V and 208Y/120 V systems. Used in the √3 formula as if they were line to line, they overstate the current by a factor of 1.732; the voltage selector prevents that.
Using a motor's shaft kW as its input
A motor rated 7.5 kW delivers that power at the shaft and draws more from the supply because of its efficiency. For current, the input kW is needed; the hp to kW converter adds efficiency to get it.
Mixing up kW and kVA
Generators, transformers and UPS units are rated in kVA. Entering a kVA rating as kW and also applying a power factor below 1 inflates the current; kVA ratings belong in the kVA to amps converter, which needs no power factor.
Frequently asked questions
How many amps is 10 kW at 240 V?
At power factor 1, 10 kW at 240 V single phase is 41.67 A. At 120 V it would be 83.33 A.
How many amps is 10 kW at 480 V three phase?
At power factor 1 it is 12.03 A per line; at PF 0.9 it is 13.36 A. The same load at 208 V three phase and PF 1 draws 27.76 A.
When should line-to-neutral voltage be selected?
When the voltage known for the system is phase to neutral, such as the 277 V of a 480Y/277 V system or the 120 V of a 208Y/120 V system. The converter then works with the corresponding line-to-line voltage.
Is a kW rating the same as a kVA rating?
Only at power factor 1. kW is real power and kVA apparent power; kW = kVA × PF. A load rated 10 kW at PF 0.8 needs 12.5 kVA of supply capacity.
Does the converter give the wire size for the load?
No. Wire size depends on the conductor ampacity at its terminations and insulation temperature, any adjustment and correction factors, and voltage drop. The ampacity and voltage drop calculators cover those checks.