In order to convert current intensity (in amperes [A]) into active power (in watts [W]) and apparent power (in volt-amperes [VA]), you have to know the voltage of the mains.

In the charts below, you will find a quick conversion of the number of amperes.

Attention: we use cos φ = 0.8. If you are dealing with a different cos φ, you can use the formulas for calculating the active power.

Single-phase:
 Psingle-phase [W] Ssingle-phase [VA] Psingle-phase [W] Ssingle-phase [VA] I [A] U = 115V U = 230V 0.1 9.2 11.5 18.4 23 0.25 23 28.75 46 57.5 0.5 46 57.5 92 115 0.75 69 86.25 138 172.5 1 92 115 184 230 1.25 115 143.75 230 287.5 1.5 138 172.5 276 345 1.75 161 201.25 322 402.5 2 184 230 368 460 2.25 207 258.75 414 517.5 2.5 230 287.5 460 575 2.75 253 316.25 506 632.5 3 276 345 552 690 3.25 299 373.75 598 747.5 3.5 322 402.5 644 805 3.75 345 431.25 690 862.5 4 368 460 736 920

Used formulas:
• Psingle-phase = U*I*cos φ
• Ssingle-phase = U*I

Three-phase:
 Pthree-phase [W] Sthree-phase [VA] Pthree-phase [W] Sthree-phase [VA] I [A] U = 230V U = 400V 0.1 31.87 39.84 55.43 69.28 0.25 79.67 99.59 138.56 173.21 0.5 159.35 199.19 277.13 346.41 0.75 239.02 298.78 415.69 519.62 1 318.70 398.37 554.26 692.82 1.25 398.37 497.96 692.82 866.03 1.5 478.05 597.56 831.38 1039.23 1.75 557.72 697.15 969.95 1212.44 2 637.39 796.74 1108.51 1385.64 2.25 717.07 896.34 1247.08 1558.85 2.5 796.74 995.93 1385.64 1732.05 2.75 876.42 1095.52 1524.20 1905.26 3 956.09 1195.11 1662.77 2078.46 3.25 1035.77 1294.71 1801.33 2251.67 3.5 1115.44 1394.30 1939.90 2424.87 3.75 1195.11 1493.89 2078.46 2598.08 4 1274.79 1593.49 2217.02 2771.28

Used formulas:
• Pthree-phase = U*I*cos φ*√3
• Sthree-phase = U*I*√3

When determining the power of the load, we first check whether it is a single-phase or a three-phase load.

Single-phase:
The active power P (in watts) equals the voltage (in volts) multiplied by the current (in amperes) and cos φ.
Psingle-phase =U*I*cos φ [W]

The apparent power S (in volt-amperes) equals the voltage (in volts) multiplied by the current (in amperes).
Ssingle-phase = U*I [VA]

Three-phase:
The active power P (in watts) equals the voltage (in volts) multiplied by the current (in amperes), cos φ and the square root of three.
Pthree-phase = U*I*cos φ*√3 [W]

The apparent power S (in volt-amperes) equals the voltage (in volts) multiplied by the current (in amperes) and the square root of three.

Sthree-phase = U*I*√3 [VA]

If you want to convert active power P in watts (W) into apparent power S in volt-amperes (VA), you can use this formula:
Sthree-phase = Pthree-phase/cos φ

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