Kilowatts (kW) to Amps Electrical Conversion Calculator

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How to Convert Kilowatts to Amps

It is possible to convert kilowatts (kW) to amps using the Watt’s Law power formula. The power formula states that current = power ÷ voltage.

To adapt the power formula to using kilowatts, first start by converting kilowatts to watts, which can be done by multiplying the power in kilowatts by 1,000 to get the number of watts.

Then, apply the power formula by dividing the power (in watts) by the voltage (in volts) to find the current (in amps).

kW to Amps Formula

Thus, for DC and single-phase AC circuits, the formula to convert kilowatts to amps is:[1]

I(A) = P(kW) × 1,000 / V(V)

The current I in amps is equal to the power P in kilowatts divided by the voltage V in volts.

Power triangle illustrating the formula to convert kilowatts to amps with amps being equal to kilowatts times 1,000 divided by volts

For example, find the current of a circuit with 1 kW of power at 120 volts.

I(A) = 1 kW × 1,000 / 120 V
I(A) = 1,000 W / 120
I(A) = 8.33 A

So, generating 1 kW of power at 120 volts will draw 8.33 amps of current.

How to Account for Motor Efficiency and Power Factor

Equipment is often not 100% efficient with power usage, and this must be factored in to find the number of amps consumed for a given output power. Efficiency of the motor η, is defined as the ratio of power output to power input.

To find the input current required to achieve a certain motor output power, use the following equation.

I(A) = P(kW) × 1,000 / V(V) × η

Thus, the current I in amps is equal to the power P in kilowatts divided by the voltage V in volts times the efficiency η.

The magnitude of real and reactive together in alternating current power is called the apparent power, and the power factor is the ratio of real power to apparent power.[2]

To find the input current required to achieve a certain motor output power accounting for power factor and efficiency, use the following equation.[1]

I(A) = P(kW) × 1,000 / V(V) × η × PF

The current I in amps is equal to the power P in kilowatts divided by the voltage V in volts times the efficiency η times the power factor PF. Try our power factor calculator to get the power factor if needed.

For example, let’s find the current of a 5 kW motor with an efficiency of 75% and power factor of 0.8 at 240 volts.

I(A) = 5 kW × 1,000 / 240 V × 0.75 × 0.8
I(A) = 5,000 W / 144 V
I(A) = 34.72 A

In this example, the 5 kW motor will draw 34.72 amps of current.

How to Find the Current of a Three-Phase AC Circuit

The formulas to convert kilowatts to amps for a three-phase AC circuit are a little different from the formula for a single-phase circuit. Use one of the formulas below for line to line or line to neutral RMS voltages.[1][3]

Using Line to Line Voltage

I(A) = P(kW) × 1,000 / VL-L(V) × η × PF × √3

This formula measures the current draw for one pair of wires in the three-phase system; to calculate the current for all three pairs of wires, you need to multiply the result by three.

Using Line to Neutral Voltage

I(A) = P(kW) × 1,000 / VL-N(V) × η × PF × 3

This formula measures the current draw for all three wires in the three-phase system; to calculate the current for a single wire, you need to divide the result by three.

For example, find the current usage of a 25 kW three-phase motor with an efficiency of 80% and a power factor of 1 at 240 volts (line to line).

I(A) = 25 kW × 1,000 / 240 V × 0.8 × 1 × √3
I(A) = 25,000 W / 332.55 V
I(A) = 75.18 A

To convert watts to amps, use our watts to amps conversion calculator.

Motor Current Ratings (Three-Phase AC)

Motor current ratings based on kilowatt output at 120, 208, 240, 277, and 480 volts three-phase AC with an efficiency of 0.8 and a power-factor of 1.
Power Current at 120V Current at 208V Current at 240V Current at 277V Current at 480V
1 kW 6.014 A 3.47 A 3.007 A 2.605 A 1.504 A
2 kW 12.028 A 6.939 A 6.014 A 5.211 A 3.007 A
3 kW 18.042 A 10.409 A 9.021 A 7.816 A 4.511 A
4 kW 24.056 A 13.879 A 12.028 A 10.421 A 6.014 A
5 kW 30.07 A 17.348 A 15.035 A 13.027 A 7.518 A
6 kW 36.084 A 20.818 A 18.042 A 15.632 A 9.021 A
7 kW 42.098 A 24.288 A 21.049 A 18.238 A 10.525 A
8 kW 48.113 A 27.757 A 24.056 A 20.843 A 12.028 A
9 kW 54.127 A 31.227 A 27.063 A 23.448 A 13.532 A
10 kW 60.141 A 34.697 A 30.07 A 26.054 A 15.035 A
15 kW 90.211 A 52.045 A 45.105 A 39.081 A 22.553 A
20 kW 120.28 A 69.393 A 60.141 A 52.107 A 30.07 A
25 kW 150.35 A 86.741 A 75.176 A 65.134 A 37.588 A
30 kW 180.42 A 104.09 A 90.211 A 78.161 A 45.105 A
35 kW 210.49 A 121.44 A 105.25 A 91.188 A 52.623 A
40 kW 240.56 A 138.79 A 120.28 A 104.21 A 60.141 A
45 kW 270.63 A 156.13 A 135.32 A 117.24 A 67.658 A
50 kW 300.7 A 173.48 A 150.35 A 130.27 A 75.176 A
55 kW 330.77 A 190.83 A 165.39 A 143.3 A 82.693 A
60 kW 360.84 A 208.18 A 180.42 A 156.32 A 90.211 A
65 kW 390.91 A 225.53 A 195.46 A 169.35 A 97.729 A
70 kW 420.98 A 242.88 A 210.49 A 182.38 A 105.25 A
75 kW 451.05 A 260.22 A 225.53 A 195.4 A 112.76 A
80 kW 481.13 A 277.57 A 240.56 A 208.43 A 120.28 A
85 kW 511.2 A 294.92 A 255.6 A 221.46 A 127.8 A
90 kW 541.27 A 312.27 A 270.63 A 234.48 A 135.32 A
95 kW 571.34 A 329.62 A 285.67 A 247.51 A 142.83 A
100 kW 601.41 A 346.97 A 300.7 A 260.54 A 150.35 A
125 kW 751.76 A 433.71 A 375.88 A 325.67 A 187.94 A
150 kW 902.11 A 520.45 A 451.05 A 390.81 A 225.53 A
175 kW 1,052.5 A 607.19 A 526.23 A 455.94 A 263.12 A
200 kW 1,202.8 A 693.93 A 601.41 A 521.07 A 300.7 A
225 kW 1,353.2 A 780.67 A 676.58 A 586.21 A 338.29 A
250 kW 1,503.5 A 867.41 A 751.76 A 651.34 A 375.88 A
275 kW 1,653.9 A 954.15 A 826.93 A 716.48 A 413.47 A
300 kW 1,804.2 A 1,040.9 A 902.11 A 781.61 A 451.05 A
325 kW 1,954.6 A 1,127.6 A 977.29 A 846.75 A 488.64 A
350 kW 2,104.9 A 1,214.4 A 1,052.5 A 911.88 A 526.23 A
375 kW 2,255.3 A 1,301.1 A 1,127.6 A 977.01 A 563.82 A
400 kW 2,405.6 A 1,387.9 A 1,202.8 A 1,042.1 A 601.41 A
425 kW 2,556 A 1,474.6 A 1,278 A 1,107.3 A 638.99 A
450 kW 2,706.3 A 1,561.3 A 1,353.2 A 1,172.4 A 676.58 A
475 kW 2,856.7 A 1,648.1 A 1,428.3 A 1,237.6 A 714.17 A
500 kW 3,007 A 1,734.8 A 1,503.5 A 1,302.7 A 751.76 A
525 kW 3,157.4 A 1,821.6 A 1,578.7 A 1,367.8 A 789.35 A
550 kW 3,307.7 A 1,908.3 A 1,653.9 A 1,433 A 826.93 A
575 kW 3,458.1 A 1,995.1 A 1,729 A 1,498.1 A 864.52 A
600 kW 3,608.4 A 2,081.8 A 1,804.2 A 1,563.2 A 902.11 A
625 kW 3,758.8 A 2,168.5 A 1,879.4 A 1,628.4 A 939.7 A
650 kW 3,909.1 A 2,255.3 A 1,954.6 A 1,693.5 A 977.29 A
675 kW 4,059.5 A 2,342 A 2,029.7 A 1,758.6 A 1,014.9 A
700 kW 4,209.8 A 2,428.8 A 2,104.9 A 1,823.8 A 1,052.5 A
725 kW 4,360.2 A 2,515.5 A 2,180.1 A 1,888.9 A 1,090 A
750 kW 4,510.5 A 2,602.2 A 2,255.3 A 1,954 A 1,127.6 A
775 kW 4,660.9 A 2,689 A 2,330.5 A 2,019.2 A 1,165.2 A
800 kW 4,811.3 A 2,775.7 A 2,405.6 A 2,084.3 A 1,202.8 A
825 kW 4,961.6 A 2,862.5 A 2,480.8 A 2,149.4 A 1,240.4 A
850 kW 5,112 A 2,949.2 A 2,556 A 2,214.6 A 1,278 A
875 kW 5,262.3 A 3,035.9 A 2,631.2 A 2,279.7 A 1,315.6 A
900 kW 5,412.7 A 3,122.7 A 2,706.3 A 2,344.8 A 1,353.2 A
925 kW 5,563 A 3,209.4 A 2,781.5 A 2,410 A 1,390.8 A
950 kW 5,713.4 A 3,296.2 A 2,856.7 A 2,475.1 A 1,428.3 A
975 kW 5,863.7 A 3,382.9 A 2,931.9 A 2,540.2 A 1,465.9 A
1000 kW 6,014.1 A 3,469.7 A 3,007 A 2,605.4 A 1,503.5 A

Motor Current Ratings (Single-Phase AC)

Motor current ratings based on kilowatt output at 120 and 240 volts single-phase AC with an efficiency of 0.8 and a power-factor of 1.
Power Current at 120V Current at 240V
1 kW 10.417 A 5.208 A
2 kW 20.833 A 10.417 A
3 kW 31.25 A 15.625 A
4 kW 41.667 A 20.833 A
5 kW 52.083 A 26.042 A
6 kW 62.5 A 31.25 A
7 kW 72.917 A 36.458 A
8 kW 83.333 A 41.667 A
9 kW 93.75 A 46.875 A
10 kW 104.17 A 52.083 A
15 kW 156.25 A 78.125 A
20 kW 208.33 A 104.17 A
25 kW 260.42 A 130.21 A
30 kW 312.5 A 156.25 A
35 kW 364.58 A 182.29 A
40 kW 416.67 A 208.33 A
45 kW 468.75 A 234.38 A
50 kW 520.83 A 260.42 A
55 kW 572.92 A 286.46 A
60 kW 625 A 312.5 A
65 kW 677.08 A 338.54 A
70 kW 729.17 A 364.58 A
75 kW 781.25 A 390.63 A
80 kW 833.33 A 416.67 A
85 kW 885.42 A 442.71 A
90 kW 937.5 A 468.75 A
95 kW 989.58 A 494.79 A
100 kW 1,041.7 A 520.83 A
125 kW 1,302.1 A 651.04 A
150 kW 1,562.5 A 781.25 A
175 kW 1,822.9 A 911.46 A
200 kW 2,083.3 A 1,041.7 A
225 kW 2,343.8 A 1,171.9 A
250 kW 2,604.2 A 1,302.1 A
275 kW 2,864.6 A 1,432.3 A
300 kW 3,125 A 1,562.5 A
325 kW 3,385.4 A 1,692.7 A
350 kW 3,645.8 A 1,822.9 A
375 kW 3,906.3 A 1,953.1 A
400 kW 4,166.7 A 2,083.3 A
425 kW 4,427.1 A 2,213.5 A
450 kW 4,687.5 A 2,343.8 A
475 kW 4,947.9 A 2,474 A
500 kW 5,208.3 A 2,604.2 A
525 kW 5,468.8 A 2,734.4 A
550 kW 5,729.2 A 2,864.6 A
575 kW 5,989.6 A 2,994.8 A
600 kW 6,250 A 3,125 A
625 kW 6,510.4 A 3,255.2 A
650 kW 6,770.8 A 3,385.4 A
675 kW 7,031.3 A 3,515.6 A
700 kW 7,291.7 A 3,645.8 A
725 kW 7,552.1 A 3,776 A
750 kW 7,812.5 A 3,906.3 A
775 kW 8,072.9 A 4,036.5 A
800 kW 8,333.3 A 4,166.7 A
825 kW 8,593.8 A 4,296.9 A
850 kW 8,854.2 A 4,427.1 A
875 kW 9,114.6 A 4,557.3 A
900 kW 9,375 A 4,687.5 A
925 kW 9,635.4 A 4,817.7 A
950 kW 9,895.8 A 4,947.9 A
975 kW 10,156 A 5,078.1 A
1000 kW 10,417 A 5,208.3 A
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References

  1. Miller, C., NFPA's Electrical References, National Fire Protection Association, 2004, Jones & Bartlett Learning, 67-75. https://www.google.com/books/edition/NFPA_s_Electrical_References/raUyIi7i-asC
  2. Fiore, J., AC Electrical Circuit Analysis - A Practical Approach, 2022, 274. http://www.dissidents.com/resources/ACElectricalCircuitAnalysis.pdf
  3. Miller, C., Ugly’s Electrical References, 2020 Edition, 2020, Jones & Bartlett Learning, 16-23. https://books.google.com/books?id=1kS8DwAAQBAJ