Amps to Kilowatts Calculator
Convert amps to kilowatts for DC, single-phase and three-phase circuits, with power factor, kVA, kWh per day or month and an optional energy cost.
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How the Amps to Kilowatts Calculator Formula Works
Amps measure how much current flows. Kilowatts measure how fast energy is used. To get from one to the other you need the voltage, and for alternating current you also need the power factor. The basic step is Watt's law: power in watts equals current in amps times voltage in volts. Divide by 1,000 and you have kilowatts.
For direct current, that is the whole story: kW = A x V / 1,000. A 50 amp load on a 12 volt battery bank is 600 watts, or 0.6 kW.
For single-phase alternating current, such as a household 120 or 240 volt circuit, the power factor comes in. Volts times amps gives the apparent power in volt-amperes. The power factor, a number from 0 to 1, tells you how much of that does real work. Multiply by it to get real power: kW = A x V x PF / 1,000. Resistive loads such as heaters sit at 1. Motors are usually lower.
Three-phase circuits carry power on three conductors, and for a balanced load measured line-to-line the formula gains a factor of the square root of 3, about 1.732: kW = 1.732 x A x V x PF / 1,000. Leaving that factor out is the most common three-phase mistake.
Once you have kW, energy is simple. A 1 kW load running for one hour uses 1 kWh, so kWh per day is kW times hours per day, and kWh per month is that times the days in use. Multiply by your price per kWh for a running cost. Apparent power in kVA is kW divided by the power factor, so the page shows both.
DC: kW = A × V / 1000 | AC single-phase: kW = A × V × PF / 1000 | AC three-phase line-to-line: kW = 1.732 × A × V × PF / 1000 | kVA = kW / PF | kWh = kW × hours- AACurrent in amps, from a nameplate, a meter or a breaker rating.
- VVVoltage. For three-phase, the line-to-line voltage such as 208, 400 or 480 volts.
- PFratioPower factor from 0 to 1. Use 1 for resistive loads. DC ignores it.
- kWkWReal power, in thousands of watts.
- kVAkVAApparent power, volts times amps (times 1.732 for three-phase) divided by 1,000.
- + 1 more input below
- A
- A
- Current in amps, from a nameplate, a meter or a breaker rating.
- V
- V
- Voltage. For three-phase, the line-to-line voltage such as 208, 400 or 480 volts.
- PF
- ratio
- Power factor from 0 to 1. Use 1 for resistive loads. DC ignores it.
- kW
- kW
- Real power, in thousands of watts.
- kVA
- kVA
- Apparent power, volts times amps (times 1.732 for three-phase) divided by 1,000.
- hours, days, price
- h, days, $/kWh
- Optional, to turn kW into kWh per day, kWh per month and a monthly cost.
Using the Amps to Kilowatts Calculator
Enter circuit type
Choose from AC, single-phase, DC (direct current), AC, three-phase (line-to-line voltage).
Enter currentA
Type the figure you already have, then press Calculate.
Enter voltageV
Type the figure you already have, then press Calculate.
Enter power factor (ignored for dc; use 1 for a resistive load)
Any value between 0.01 and 1.
Enter hours of use per day (optional)h
Any value between 0 and 24. This one is optional.
Enter days of use per month (optional)days
Any value between 0 and 31. This one is optional.
Enter price per kwh (optional, 0.16 is a placeholder)$
Type the figure you already have, then press Calculate. This one is optional.
Read the result
Press Calculate to update the result. Until you do, the last result is dimmed and marked as out of date, so you always know which numbers belong to the values in the boxes.
A Real Worked Example
A 30 amp circuit on a 240 volt single-phase supply with a power factor of 1 carries 30 × 240 × 1 / 1,000 = 7.200 kW. Apparent power is the same, 7.200 kVA, because the power factor is 1.
Run for 8 hours a day on 30 days a month, that is 57.60 kWh per day and 1,728.0 kWh per month. At the placeholder price of $0.16 per kWh the energy costs about $276.48 a month. Swap in your own rate and hours.
200 amps at 240 volts
How much is 200 amps in kilowatts? On a 240 volt single-phase supply at a power factor of 1, 200 × 240 / 1,000 = 48.000 kW. Running that for one hour would use 48.00 kWh.
That is the top of what a 200 amp service can deliver, not what a home uses. Most homes draw a small fraction of it at any moment, so use measured or expected current for energy estimates, and leave panel sizing to the code and an electrician.
100 amps three-phase at 480 volts, PF 0.85
A three-phase motor load draws 100 amps at 480 volts line-to-line with a power factor of 0.85. Apparent power is 1.732 × 100 × 480 / 1,000 = 83.138 kVA. Real power is 83.138 × 0.85 = 70.668 kW.
Run 10 hours a day for 22 days, it uses 706.68 kWh per day and 15,546.9 kWh per month. At a placeholder $0.12 per kWh that is about $1,865.63.
DC: 50 amps at 12 volts
A 12 volt DC system carrying 50 amps delivers 50 × 12 / 1,000 = 0.600 kW, which is 600 watts. Power factor does not apply to DC, so the page ignores that box.
Run for 5 hours a day over 30 days, the load uses 3.00 kWh per day and 90.0 kWh per month. No price is entered, so no cost is shown.
10 amps at 220 volts, PF 0.8
A motor draws 10 amps from a 220 volt single-phase supply at a power factor of 0.8. Apparent power is 10 × 220 / 1,000 = 2.200 kVA and real power is 2.200 × 0.8 = 1.760 kW.
At PF 1 the same current would be 2.200 kW. Over 4 hours a day for 30 days, the motor uses 7.04 kWh per day and 211.2 kWh per month, costing about $31.68 at a placeholder $0.15 per kWh.
50 amps three-phase at 208 volts, PF 0.9
A three-phase load draws 50 amps at 208 volts line-to-line with a power factor of 0.9. Apparent power is 1.732 × 50 × 208 / 1,000 = 18.013 kVA and real power is 16.212 kW.
Run 16 hours a day for 26 days, it uses 259.39 kWh per day and 6,744.2 kWh per month. At a placeholder $0.14 per kWh the monthly cost is about $944.19.
What Else to Know
How to Convert Amps to Kilowatts
The conversion needs three numbers: the current in amps, the voltage, and for AC the power factor. Multiply them, divide by 1,000, and the answer is kilowatts. The calculator does this for three circuit types, the same three the watts to amps calculator uses, so you can move between the two pages without changing how you think about the circuit.
Pick DC for batteries, solar arrays and vehicles, single-phase AC for most household and small commercial circuits, and three-phase AC for motors and larger equipment. The result panel shows real power in kW, apparent power in kVA and the same real power in watts.
The optional energy boxes turn the power into kWh per day, kWh per month and a monthly cost. Leave them as they are if you only need the kilowatts.
Amps to kW Formulas for Each Circuit Type
For DC the formula is kW = A x V / 1,000. For single-phase AC it is kW = A x V x PF / 1,000. For three-phase AC measured line-to-line it is kW = 1.732 x A x V x PF / 1,000, where 1.732 is the square root of 3. The three-phase relationship comes from the fact that the voltage between two conductors of a balanced three-phase supply is 1.732 times the voltage of a single phase, as the Wikipedia article on three-phase power explains.
The single-phase and three-phase tables list kilowatts for common currents and voltages at a power factor of 1, so you can read an answer such as 100 amps three-phase at 480 volts, which is 83.14 kW, without running anything. Reverse the formula to go from kW to amps, or use the watts to amps calculator.
This page assumes a balanced three-phase load and line-to-line voltage. If you only know the line-to-neutral voltage, multiply it by 1.732 before you enter it.
Power Factor and the Difference Between kW and kVA
Volts times amps is apparent power, measured in volt-amperes. Real power, the part that does work, is apparent power times the power factor. For a heater the two are equal. For a motor, compressor or transformer, the current has a magnetic part that moves back and forth without doing work, so the power factor is below 1 and kW is less than kVA.
The power factor table shows the effect for 100 amps at 240 volts. At a power factor of 1 the load is 24 kW. At 0.8 it is 19.2 kW, even though the current and the apparent power are unchanged.
If you do not know the power factor, use the nameplate value or a measured figure. For resistive loads use 1. Utilities and meters report what actually happens, so the calculated number is a planning estimate.
How Many Kilowatts Is 1 Amp, and How Many Amps Is 1 kW?
There is no single answer, because the voltage sets the conversion. One amp at 120 volts is 0.12 kW, at 240 volts it is 0.24 kW, and at 12 volts it is 0.012 kW. The one amp table lists single-phase and three-phase values for common voltages.
Going the other way, 1 kW is 8.33 amps at 120 volts and 4.17 amps at 240 volts, both at a power factor of 1. A lower power factor means more amps for the same kilowatts, which is why the 1 kW table shows PF 1 and PF 0.8 side by side.
For larger values, scale up. The questions people ask most often, such as 200 amps, 240 amps, 100 amps three-phase and 50 amps, are answered in the FAQ and in the tables.
From Kilowatts to kWh and Running Cost
Power is a rate and energy is an amount. A 1 kW load running for one hour uses one kilowatt-hour, which the Wikipedia article on the kilowatt-hour gives as 3.6 megajoules. To find kWh, multiply kW by hours. The calculator multiplies again by the days of use to give a monthly figure.
The cost is kWh per month times your price per kWh. The 0.16 in the price box is a placeholder, not a quoted rate. Look at your bill for the real figure, which may change with the time of day, the season or the amount you use.
The energy table gives monthly kWh and cost for steady loads at three example prices. Remember that thermostat-controlled and motor loads do not draw full current all the time, so use typical running hours.
Typical Circuits Converted to Kilowatts
The circuits table converts some common circuit sizes into kilowatts. A 15 amp circuit at 120 volts is 1.8 kW, a 30 amp circuit at 240 volts is 7.2 kW and a 40 amp circuit at 240 volts is 9.6 kW. These are circuit sizes used as examples, not the ratings of any product.
A circuit rating is a ceiling. The code limits how much of it a continuous load may use, so a device that runs for three hours or more is sized with room to spare. The watts to amps calculator page explains the 80 percent continuous load idea in a worked example.
If you have a nameplate, use its amps and its voltage. If the nameplate gives watts, the watts to amps calculator works in the other direction.
Accuracy, Limits and Electrical Safety
This calculator gives estimates for planning. It assumes steady current, a fixed power factor and, for three-phase, a balanced load at line-to-line voltage. It does not model harmonics, voltage drop, start-up current or unbalanced phases.
Do not use it on its own to size conductors, breakers, fuses, generators or transformers. Follow the National Electrical Code and your local code, and have a licensed electrician size and install wiring and breakers. Work on live equipment is dangerous.
For related conversions, see the watts to amps calculator for the reverse direction, the percentage calculator for comparing energy use and costs, and the linear interpolation calculator for reading a value between two rows of a table.
Reference Tables
| Amps | 120 V | 208 V | 220 V | 230 V | 240 V |
|---|---|---|---|---|---|
| 1 | 0.120 | 0.208 | 0.220 | 0.230 | 0.240 |
| 5 | 0.600 | 1.040 | 1.100 | 1.150 | 1.200 |
| 10 | 1.200 | 2.080 | 2.200 | 2.300 | 2.400 |
| 15 | 1.800 | 3.120 | 3.300 | 3.450 | 3.600 |
| 20 | 2.400 | 4.160 | 4.400 | 4.600 | 4.800 |
| 30 | 3.600 | 6.240 | 6.600 | 6.900 | 7.200 |
| 40 | 4.800 | 8.320 | 8.800 | 9.200 | 9.600 |
| 50 | 6.000 | 10.400 | 11.000 | 11.500 | 12.000 |
| 100 | 12.000 | 20.800 | 22.000 | 23.000 | 24.000 |
| 200 | 24.000 | 41.600 | 44.000 | 46.000 | 48.000 |
| Amps | 208 V | 240 V | 400 V | 480 V |
|---|---|---|---|---|
| 10 | 3.60 | 4.16 | 6.93 | 8.31 |
| 25 | 9.01 | 10.39 | 17.32 | 20.78 |
| 50 | 18.01 | 20.78 | 34.64 | 41.57 |
| 100 | 36.03 | 41.57 | 69.28 | 83.14 |
| 150 | 54.04 | 62.35 | 103.92 | 124.71 |
| 200 | 72.05 | 83.14 | 138.56 | 166.28 |
| 400 | 144.11 | 166.28 | 277.13 | 332.55 |
| Power factor | Real power (kW) | Apparent power (kVA) | Share of kVA that does work |
|---|---|---|---|
| 1.00 | 24.00 | 24.00 | 100 percent |
| 0.95 | 22.80 | 24.00 | 95 percent |
| 0.90 | 21.60 | 24.00 | 90 percent |
| 0.85 | 20.40 | 24.00 | 85 percent |
| 0.80 | 19.20 | 24.00 | 80 percent |
| 0.70 | 16.80 | 24.00 | 70 percent |
| 0.60 | 14.40 | 24.00 | 60 percent |
| Voltage | 1 amp single-phase (kW) | 1 amp three-phase (kW) | 1 amp single-phase (W) |
|---|---|---|---|
| 12 V | 0.0120 | 0.0208 | 12.0 |
| 24 V | 0.0240 | 0.0416 | 24.0 |
| 48 V | 0.0480 | 0.0831 | 48.0 |
| 120 V | 0.1200 | 0.2078 | 120.0 |
| 208 V | 0.2080 | 0.3603 | 208.0 |
| 220 V | 0.2200 | 0.3811 | 220.0 |
| 230 V | 0.2300 | 0.3984 | 230.0 |
| 240 V | 0.2400 | 0.4157 | 240.0 |
| 277 V | 0.2770 | 0.4798 | 277.0 |
| 400 V | 0.4000 | 0.6928 | 400.0 |
| 480 V | 0.4800 | 0.8314 | 480.0 |
| Voltage | Single-phase, PF 1 | Single-phase, PF 0.8 | Three-phase, PF 1 | Three-phase, PF 0.8 |
|---|---|---|---|---|
| 120 V | 8.33 | 10.42 | 4.81 | 6.01 |
| 208 V | 4.81 | 6.01 | 2.78 | 3.47 |
| 220 V | 4.55 | 5.68 | 2.62 | 3.28 |
| 230 V | 4.35 | 5.43 | 2.51 | 3.14 |
| 240 V | 4.17 | 5.21 | 2.41 | 3.01 |
| 400 V | 2.50 | 3.12 | 1.44 | 1.80 |
| 480 V | 2.08 | 2.60 | 1.20 | 1.50 |
| Load (kW) | kWh per day | kWh per month | At $0.10 per kWh | At $0.16 per kWh | At $0.25 per kWh |
|---|---|---|---|---|---|
| 0.5 | 4.0 | 120 | $12.00 | $19.20 | $30.00 |
| 1.0 | 8.0 | 240 | $24.00 | $38.40 | $60.00 |
| 2.0 | 16.0 | 480 | $48.00 | $76.80 | $120.00 |
| 4.8 | 38.4 | 1,152 | $115.20 | $184.32 | $288.00 |
| 7.2 | 57.6 | 1,728 | $172.80 | $276.48 | $432.00 |
| 10.0 | 80.0 | 2,400 | $240.00 | $384.00 | $600.00 |
| Circuit | Amps | Volts | Power factor | Real power (kW) |
|---|---|---|---|---|
| Small appliance circuit | 15 | 120 | 1.00 | 1.80 |
| Kitchen or workshop circuit | 20 | 120 | 1.00 | 2.40 |
| Clothes dryer circuit | 30 | 240 | 1.00 | 7.20 |
| Electric vehicle charging circuit | 32 | 240 | 1.00 | 7.68 |
| Electric range circuit | 40 | 240 | 1.00 | 9.60 |
| Motor on a 208 V three-phase supply | 25 | 208 | 0.85 | 7.66 |
| Motor on a 480 V three-phase supply | 25 | 480 | 0.85 | 17.67 |
| Small panel at 100 amps, 240 V | 100 | 240 | 1.00 | 24.00 |
| Term | Meaning |
|---|---|
| Ampere (amp, A) | The unit of electric current |
| Volt (V) | The unit of electric potential, the push behind the current |
| Watt (W) and kilowatt (kW) | Real power. 1 kW is 1,000 W |
| Apparent power (VA, kVA) | Volts times amps, before power factor is applied |
| Power factor (PF) | Real power divided by apparent power, from 0 to 1 |
| Line-to-line voltage | The voltage measured between two live conductors of a three-phase supply |
| Kilowatt-hour (kWh) | Energy used by a 1 kW load running for 1 hour, equal to 3.6 megajoules |
| Mistake | Effect on the answer | Fix |
|---|---|---|
| Leaving out the 1.732 on a three-phase circuit | Result is about 42 percent too low | Pick the three-phase circuit type |
| Using line-to-neutral volts with the line-to-line formula | Result is about 42 percent too low | Enter the voltage between two live conductors |
| Using PF 1 for a motor | Real power is overstated | Use the nameplate or measured PF |
| Dividing by 100 instead of 1,000 | Result is 10 times too big | kW is watts divided by 1,000 |
| Mixing kW and kVA | Billing or sizing figures do not match | kW is real power, kVA is apparent power |
| Assuming rated amps are always flowing | Energy cost is overstated | Use the typical running current and hours |
| From | To | Multiply by |
|---|---|---|
| Watts | Kilowatts | 0.001 |
| Kilowatts | Watts | 1,000 |
| Kilowatts | Megawatts | 0.001 |
| kVA | VA | 1,000 |
| Kilowatt-hours | Megajoules | 3.6 |
| Kilowatt-hours | Watt-hours | 1,000 |
Frequently Asked Questions About the Amps to Kilowatts Calculator
How do I convert amps to kW?
Multiply amps by volts to get watts, apply the power factor for AC, then divide by 1,000. For single-phase AC, kW = amps x volts x PF / 1,000. For example, 30 amps at 240 volts with a power factor of 1 is 7.2 kW. Choose the circuit type in the calculator and it handles the maths.
What is the amps to kW formula for single phase?
For single-phase AC the formula is kW = A x V x PF / 1,000. For DC, leave out the power factor: kW = A x V / 1,000. A 15 amp load at 120 volts with PF 1 is 1.80 kW, and at a power factor of 0.8 it is 1.44 kW.
What is the amp to kW 3 phase formula?
For a balanced three-phase load measured line-to-line, kW = 1.732 x A x V x PF / 1,000. The 1.732 is the square root of 3. As an example, 50 amps at 208 volts and PF 0.9 is 16.21 kW. The same current at 480 volts is 37.41 kW.
How many kilowatts is 1 amp?
It depends on the voltage. At 120 volts, 1 amp is 0.120 kW. At 240 volts it is 0.24 kW, and at 12 volts DC it is 0.012 kW. On a three-phase 480 volt circuit, 1 amp is 0.831 kW at PF 1. The table above lists more voltages.
How many amps are in 1 kW?
Divide 1,000 by the voltage and the power factor. At 120 volts and PF 1, 1 kW is 8.33 amps. At 240 volts it is 4.17 amps, and at 240 volts with PF 0.8 it is 5.21 amps. Three-phase at 480 volts and PF 1 is 1.20 amps.
How much is 200 amps in kilowatts?
At 240 volts single-phase and a power factor of 1, 200 amps is 48 kW. At 120 volts it is 24 kW, and on a 480 volt three-phase supply it is 166.3 kW. A 200 amp service is a rating, not a continuous load, so real use is usually far lower.
How many kW is 240 amps?
At 240 volts single-phase and PF 1, 240 amps is 57.60 kW. At 208 volts three-phase it is 86.46 kW, and at 480 volts three-phase it is 199.53 kW. Enter your own voltage and power factor in the calculator for an exact figure.
How many kW is 100 amps 3 phase?
At PF 1, 100 amps three-phase is 36.03 kW at 208 volts, 69.28 kW at 400 volts and 83.14 kW at 480 volts. At 480 volts and PF 0.85 it falls to 70.67 kW, with 83.14 kVA of apparent power.
How many kW is 50 amps?
At 240 volts single-phase and PF 1, 50 amps is 12.0 kW. At 120 volts it is 6.0 kW, at 208 volts single-phase 10.40 kW, and at 12 volts DC 0.6 kW. Voltage matters as much as current, so always check which supply the 50 amps is drawn from before comparing figures.
What is 1 amp to kW at 220 volts?
At 220 volts single-phase and PF 1, 1 amp is 0.22 kW, or 220 watts. With a power factor of 0.8 the real power is 0.176 kW, while the apparent power stays at 0.22 kVA. Enter 1 amp, 220 volts and your own power factor in the calculator to check.
What is 10 amps to kW at 220 volts?
At 220 volts single-phase and PF 1, 10 amps is 2.2 kW. At PF 0.8 it is 1.76 kW real power from 2.2 kVA apparent power. Multiply by the number of hours to get kWh, so 4 hours at PF 0.8 uses about 7 kWh, and enter your hours to see the energy.
How many kW is 30 amps at 240 volts?
At 240 volts single-phase and PF 1, 30 amps is 7.2 kW. Run for 8 hours that is 57.6 kWh, and over 30 days 1,728 kWh. A circuit rated for 30 amps should not carry that continuously, so check the continuous load rules.
What power factor should I use?
Use 1 for resistive loads such as heaters, water heaters, ovens and incandescent lamps. For motors, pumps, compressors and transformers use the nameplate value or a measured figure, often between 0.8 and 0.9. If you do not know it, start with 0.85 for a typical motor load and treat the result as an estimate.
Does this amps to kilowatts calculator work for DC?
Yes. Choose DC and the calculator uses kW = A x V / 1,000 with no power factor. A 50 amp load on a 12 volt battery system is 0.6 kW, and on a 48 volt system 50 amps is 2.4 kW. Battery and solar figures use this form.
How do I find kWh from amps?
First convert amps to kW, then multiply by the hours of running time. 30 amps at 240 volts is 7.2 kW, so 8 hours uses 57.6 kWh. One kWh is the energy of a 1 kW load running for one hour, which equals 3.6 megajoules.
How do I work out the monthly cost?
Multiply kWh per month by your price per kWh. For a 7.2 kW load run 8 hours a day for 30 days that is 1,728 kWh. At the placeholder price of $0.16 per kWh the cost is $276.48. Use your own utility rate for a real figure.
What is the difference between kW and kVA?
kW is real power that does work. kVA is apparent power, volts times amps before the power factor. They match when PF is 1 and kW is lower otherwise. At 100 amps and 240 volts you have 24.0 kVA, which is 19.2 kW at PF 0.8.
Can I use line-to-neutral voltage for three-phase?
Not with this page. The three-phase option expects the line-to-line voltage, such as 208, 400 or 480 volts. If you only know the line-to-neutral voltage, multiply it by 1.732 first. For example, 277 volts line-to-neutral is 480 volts line-to-line, so enter 480 for a typical 277/480 volt system.
Can I use this to size a breaker or wire?
Use it for planning only. Wire and breaker sizing depends on the National Electrical Code, local amendments, conductor type, temperature, length and whether the load is continuous. Follow the code and have a licensed electrician size and install wiring and breakers. The result here is an estimate.
Why is my measured kW lower than the calculation?
The calculation assumes a steady current at a fixed power factor. A real meter reads the actual power factor, the actual voltage and the current that really flows. Motors cycle, heaters switch with a thermostat, and voltage sags under load. Measured kW below the estimate is common and not a fault.
How do I use this 3 phase kW calculator?
Pick the three-phase circuit type, enter the current in amps, the line-to-line voltage and the power factor. The results show real power in kW, apparent power in kVA and watts. Add hours per day, days per month and a price per kWh if you also want energy use and cost.
References
- [1] Wikipedia contributors. “Three-phase electric power.” Wikipedia. Accessed 2026-10-07.
- [2] Wikipedia contributors. “Power factor.” Wikipedia. Accessed 2026-10-07.
- [3] Wikipedia contributors. “Kilowatt-hour.” Wikipedia. Accessed 2026-10-07.
- [4] Wikipedia contributors. “Volt-ampere.” Wikipedia. Accessed 2026-10-07.
- [5] Wikipedia contributors. “National Electrical Code.” Wikipedia. Accessed 2026-10-07.
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