AMP to KW

The amps to kW calculator converts electric current in amperes (A) into real power in kilowatts (kW) with 4 inputs: current, voltage, power factor and current type. The calculator applies P(kW) = I(A) × V(V) / 1,000 for direct current (DC), multiplies by the power factor (PF) for single-phase alternating current (AC) and multiplies by √3 × PF for three-phase AC.

The calculator returns 4 results: real power in kW, apparent power in kilovolt-amperes (kVA), reactive power in kilovolt-amperes reactive (kVAR) and power in watts (W). The definitions of real, apparent and reactive power follow IEEE Standard 1459 from the Institute of Electrical and Electronics Engineers (IEEE). The voltage and current inputs are root mean square (RMS) values, the same values a multimeter or a clamp meter displays.

20 A on a 240 V single-phase circuit at PF 0.95 gives 4.56 kW, 4.8 kVA and 1.5 kVAR. The waveform shows voltage and current over time, the gauge shows kW on a scale and the power triangle shows how kW, kVA and kVAR relate.

The amps to kW formula is P(kW) = I(A) × V(V) × PF / 1,000 for single-phase AC. There are 3 versions of the amps to kW formula, one for each current type: DC, single-phase AC and three-phase AC.

The DC formula has no power factor, since DC voltage and current stay in phase. The single-phase formula multiplies by PF, the cosine of the angle between the voltage wave and the current wave. The three-phase formula multiplies by √3 (1.732) with line-to-line voltage or by 3 with line-to-neutral voltage. Nikola Tesla developed the polyphase AC system that the three-phase formula describes.

The watt (W) is the SI unit of power, named after James Watt. 1 kW equals 1,000 W, 1.341 horsepower (hp) and 3,412 BTU per hour.

The amps to kW conversion chart lists the kW value of 20 common currents from 1 A to 200 A at 7 supply voltages, from 12 V DC to 480 V three phase. The chart uses a power factor of 1. Multiply a chart value by the real power factor to get kW for motors and other inductive loads, for example × 0.8 for a load at PF 0.8.

Three-phase columns use line-to-line voltage and the current in each line. 30 A at 240 V equals 7.2 kW, and 100 A at 480 V three phase equals 83.14 kW at PF 1 or 74.82 kW at PF 0.9.

The amps to kW Excel formula is =A2*B2*C2/1000 with amps in cell A2, volts in cell B2 and power factor in cell C2. Use =SQRT(3)*A2*B2*C2/1000 for three-phase rows and =A2*B2/1000 for DC rows.

The same formulas work in Google Sheets and LibreOffice Calc. Wrap the formula in ROUND(…,2) to show 2 decimal places, and fill the formula down column D to convert a full list of loads at once.

The amps to kW equation is P = V × I × cos φ, where P is real power in watts, V is RMS voltage, I is RMS current and cos φ is the power factor. Dividing P by 1,000 gives kilowatts.

The equation connects to 2 older laws. Ohm’s law, published by Georg Ohm in 1827, states V = I × R. Joule’s law states P = I² × R for a resistor. Substituting Ohm’s law into P = V × I gives P = I² × R, so a resistive heater at PF 1 follows the same amps to kW result from either equation. The triangle above shows 20 A at 240 V and PF 0.95: 4.8 kVA of apparent power splits into 4.56 kW of real power and 1.5 kVAR of reactive power.

Amps from kW and volts equal I(A) = P(kW) × 1,000 / (V × PF) for single-phase AC. The equation rearranges the amps to kW formula to solve for current.

Cover the unknown value in the triangle to read the formula: cover I and the triangle shows P ÷ V. There are 3 worked examples:

• 3 kW at 230 V and PF 1 draws 13.04 A.
• 3 kW at 120 V and PF 1 draws 25 A.
• 15 kW at 400 V three phase and PF 0.9 draws 24.06 A per line.

The National Electrical Code (NEC, NFPA 70) limits continuous loads to 80% of the breaker rating, so size the breaker at 125% of the calculated amps. Use the kW to amps calculator to get the current and a suggested breaker size.

To convert amps to kW, multiply amps by volts, multiply by the power factor and divide by 1,000. There are 5 steps to convert amps to kW by hand:

1. Measure the current in amps with a clamp meter or read the amps on the equipment nameplate.
2. Read the supply voltage, for example 120 V, 230 V, 240 V, 400 V or 480 V.
3. Find the power factor on the nameplate. Use 1 for DC and resistive heaters, 0.8–0.9 for motors.
4. Multiply amps × volts × power factor, and multiply by 1.732 for three phase.
5. Divide the result by 1,000 to turn watts into kilowatts.

A power analyzer or a wattmeter measures kW directly and confirms the hand calculation. National Electrical Manufacturers Association (NEMA) motor nameplates list full-load amps, volts, power factor and efficiency, which supply all 4 values for the conversion.

Yes, you can convert kW to amps, if the voltage and power factor are known. Divide watts by volts × power factor: I = kW × 1,000 / (V × PF).

kW to amps conversion needs voltage. 1 kW at 120 V draws 8.33 A, and the same 1 kW at 240 V draws 4.17 A. A kW value without a voltage has no single amp equivalent. The kW to amps calculator handles DC, single-phase and three-phase supplies.

There are 4.35 amps in a kW at 230 V and 8.33 amps in a kW at 120 V, at a power factor of 1. The number of amps in a kW drops as voltage rises. The chart shows the amps in 1 kW at 8 common supply voltages:

A lower power factor increases the amps in a kW. At PF 0.8, 1 kW draws 5.43 A at 230 V and 10.42 A at 120 V.

The difference between amps and kW is that amps measure electric current and kW measure electrical power. Amps count the charge flowing each second, and kW count the energy delivered each second.

Amps decide wire and breaker size, and kW decide energy use and cost. Electricity bills charge for kilowatt-hours (kWh): a 2 kW heater running for 3 hours uses 6 kWh.

Amps vs kW vs volts compares 3 electrical quantities: current (amps), power (kW) and electric potential (volts). Power equals volts × amps, so knowing 2 of the 3 values gives the third.

The International Electrotechnical Commission (IEC) defines the volt, the ampere and the watt in the SI system, and IEC 60364 sets low-voltage installation rules using all 3 units. A 230 V circuit carrying 10 A delivers 2.3 kW at PF 1, and a 120 V circuit carrying the same 2.3 kW draws 19.17 A.