Amps tell you how much current is flowing. Kilowatts tell you how much real power that current delivers. The link between the two is voltage, and in AC circuits it also depends on power factor and on how many phases you have. That is why quick shortcuts like "just divide by 1000" go wrong so often.

This amps to kW calculator takes care of all of that. Pick DC, single-phase or three-phase, enter the voltage and current, and it gives you real power in kilowatts along with watts, apparent power and reactive power. Think of it as an amps to kilowatts calculator that does not ignore power factor. Flip the switch and it becomes a kW to amps calculator, which is handy when you are sizing a cable, a breaker or a generator for a load you already know in kW.

Below you will find the formulas, a proper walkthrough of every control on the calculator, conversion charts you can use without opening the tool, worked examples, and answers to the questions people search for most, like how many amps is 1kw and how many kW is 30 amps.

Amps to kW Formula (Quick Answer)

In the formulas below, V is voltage in volts, I is current in amps and PF is power factor, a number between 0 and 1 that says how much of the current is doing useful work. The 1.732 is the square root of 3. It turns up in three-phase maths because the three voltages are 120 degrees apart rather than lined up with each other.

For a balanced three-phase load, the line-to-line and line-to-neutral versions give nearly the same answer as long as each one is paired with its own voltage. The small gap comes from nominal voltages being rounded: 230 x 1.732 is 398.4, not exactly 400.

A quick example. A load draws 10 A from a 230 V single-phase supply at a power factor of 0.95. Real power is 230 x 10 x 0.95 / 1000 = 2.185 kW. Going the other way, 2.185 kW on the same supply needs 2185 / (230 x 0.95) = 10 A. Run those numbers through the calculator above and you will see the same figures, with the sum written out underneath.

How to Use This Amps to kW Calculator

The calculator is meant to be quick, but there is more under the hood than two boxes and a button. Here is what each part does and when you would reach for it.

Step by step

1. Choose the supply type. Tap DC, Single-phase or Three-phase. The animated strip under the title changes to match: a dotted line for DC, one sine wave for single-phase and three coloured waves for three-phase. On DC the power factor box folds away, because power factor only exists in AC circuits.
2. Pick the direction. The switch at the top right says A to kW or kW to A. A to kW turns a current into power. kW to A does the reverse, so you type the power and read the current. Your last result carries over when you flip it, so 10 A that gave 2.185 kW becomes a 2.185 kW input.
3. Enter the voltage. Use the voltage the load actually runs at. On three-phase you will see a small L-L / L-N toggle. L-L is line-to-line, the voltage between any two of the three live conductors (400 V on a typical European or UK supply, 480 V in much of North American industry). L-N is line-to-neutral, from one live conductor to neutral (230 V or 277 V). Switching between them converts your number for you: 400 becomes 230, 480 becomes 277, and any other value is divided or multiplied by 1.732.
4. Use the quick voltage buttons if one fits. One tap fills in a standard value: 12, 24, 48 and 110 V for DC; 110, 120, 230 and 240 V for single-phase; 208, 400, 415 and 480 V for three-phase line-to-line; and 120, 230, 240 and 277 V for line-to-neutral. The highlighted button tells you when the voltage you typed matches one of them.
5. Enter the current, or the power. In A to kW mode type the amps. In kW to A mode type the kilowatts. Decimals work with a dot or a comma, so 2.5 and 2,5 mean the same thing. The up and down arrow keys nudge the number, and holding Shift makes each step ten times bigger.
6. Set the power factor. Drag the slider or type a value between 0.01 and 1. It starts at 0.95. Use 1 for pure heating loads and check the nameplate for motors. If you want an amps to kW calculator with power factor built in, this is the control that matters.
7. Read the result. There is no calculate button. Everything updates while you type.

Switching units: mV, V, kV and mA, A, kA

The small unit label beside Voltage and Current is actually a button. Tap it to cycle through the units: V, kV and mV for voltage, and A, kA and mA for current. The number in the box converts automatically so the real quantity stays the same. 230 V becomes 0.23 kV and then 230000 mV. 10 A becomes 0.01 kA and then 10000 mA. The result does not change, only the way you are describing the input.

This helps when your numbers arrive in awkward sizes: a sensor that outputs milliamps, a substation rated in kV and kA, or a datasheet that lists millivolts. In kW to A mode the second box is power in kW, so only the voltage unit can be changed. The quick voltage buttons and the red reset button put the units back to V and A.

Reading the result panel

The big dial shows the main answer. The needle moves to the value and the scale resizes itself so small and large results both look sensible. Under the dial are three tiles:

• Single-phase and three-phase: Watts (real power in W), Apparent power in kVA and Reactive power in kVAR.
• DC: Watts, load resistance in ohms (volts divided by amps) and mechanical horsepower (watts divided by 745.7).

In kW to A mode on a three-phase supply the dial is labelled current per line. That is the figure you use when choosing a cable or breaker for each conductor.

The strip at the bottom writes the calculation out with your own numbers, for example the square root of 3 x 400 V x 32 A x 0.95 / 1000 = 21.062 kW. If you entered kV or mA, the strip shows the converted volts and amps so the arithmetic is easy to follow. It also doubles as the error message: if a field is empty or the power factor is out of range, it tells you what to fix and the field gets a red outline.

Copy, reset and the small touches

The green button copies your result as a plain sentence, such as "10 A at 230 V, single-phase AC, PF 0.95 = 2.185 kW", and a small Copied label pops up to confirm it worked. The red button puts voltage, current and power factor back to their defaults for the mode you are in and brings the calculator back into view if you had scrolled away. The page also scrolls the calculator into view when you change the supply type or direction, which saves a lot of thumb work on a phone.

Using it as a kW to amps calculator (three-phase too)

Switch to kW to A when the load is known in kW, for example a motor plate that says 15 kW or a generator rated at 22 kW. Choose Three-phase, make sure the L-L / L-N toggle matches the voltage you are typing, and read the line current from the dial. That makes it a working kW to amps calculator 3 phase tool as well as a single-phase one. Round the answer up when you choose protective devices, and always follow your local wiring rules rather than relying on a calculator alone.

DC, Single-Phase and Three-Phase: Which One Do You Need?

The three tabs exist because the formula changes with the type of supply. Picking the wrong one is the most common reason two calculators disagree.

DC

Batteries, solar panels and their charge controllers, vehicle and boat electrics, LED strips and the output side of most phone and laptop chargers are all DC. There is no power factor and no square root of 3: kW = volts x amps / 1000. A 12 V system pulling 100 A is 1.2 kW, and so is a 48 V system pulling 25 A. If you went looking for a DC amps to kW calculator, this is the tab you want.

Single-phase

Homes, offices, shops and most small appliances run on single-phase AC. Nominal voltage is around 120 V in North America and 230 V or 240 V in Europe, the UK, Australia, India and many other countries. A single-phase amps to kW calculator needs the power factor as well, because motors and electronics rarely sit at a perfect 1.0.

Three-phase

Workshops, farms, pumps, lifts, commercial kitchens, large air conditioning plant and rapid EV chargers use three-phase, with three live conductors that each carry current. For the same power it needs far less current per conductor. At 400 V line-to-line it is roughly a third of what a 230 V single-phase supply would need, which is why industry prefers it. This calculator works as a 3 phase amps to kW calculator and, in the other direction, as a 3 phase power calculator in kW. Always check whether the voltage you hold is line-to-line or line-to-neutral. Mixing them up is worth a factor of 1.732 in the answer.

Amps to kW Conversion Chart

An amp to kW conversion table is handy when you only need a ballpark. Every AC value below uses a power factor of 0.95, the same default the calculator opens with, so you can check any row in the tool. If your load has a different power factor, scale the figure. A power factor of 0.8, for example, gives about 84% of the number shown, because 0.8 / 0.95 is 0.84.

The jump from the single-phase bars to the three-phase ones is the whole reason three-phase exists. Same current, same power factor, but three conductors share the work at a higher voltage.

kW to Amps Conversion Chart

Going the other way, this chart answers the question "what current will my load draw?" Values assume a power factor of 0.95. The 400 V column is three-phase line-to-line, so it doubles as a quick kW to amps calculator 3 phase reference for typical European and UK supplies.

Look at how fast current falls as voltage rises. Delivering 5 kW at 12 V takes over 400 A, which means seriously thick cable, while three-phase 400 V does the same job with about 7 A per conductor. Low-voltage DC systems pay for their safety with big currents, and every extra volt of system voltage cuts the current you have to carry.

How Many Amps Is 1 kW? (And Other Common Questions)

How many amps is 1 kW?

There is no single answer, because amps depend on voltage. At a power factor of 1, one kilowatt draws this much current:

At a power factor of 0.95 add about 5% to each figure. So how many amps is 1kw on an ordinary circuit? About 4.35 A at 230 V and 8.33 A at 120 V.

How many kW is 30 amps?

At 240 V single-phase and a power factor of 1, 30 A is 7.2 kW. At a more realistic 0.95 it is 6.84 kW. On a 230 V supply it is 6.9 kW at PF 1 and about 6.56 kW at 0.95. At 120 V, 30 A is 3.6 kW at PF 1. On a 400 V three-phase supply with a power factor of 0.95, 30 A per line comes to about 19.75 kW.

How many amps is 7.2 kW?

A 7.2 kW load on 240 V single-phase draws 30 A at PF 1, which is where the 30 A figure above comes from. On 230 V it draws 31.3 A, on 120 V it draws 60 A, and on 400 V three-phase it draws 10.39 A per line.

Power Factor: Why It Changes the Answer

Power factor is the ratio of real power (kW) to apparent power (kVA). A resistive load such as a kettle or heater turns almost all of its current into heat, so its power factor is about 1. A motor needs part of its current just to build magnetic fields. That part does no useful work but still flows through the cable, so the power factor drops and the same amps deliver fewer kilowatts.

That is why an amps to kW calculator with power factor gives a more honest number than one that skips it. 10 A at 230 V is 2.3 kVA whatever the load is, but it is 2.3 kW only at PF 1. At 0.95 it is 2.185 kW, and at 0.8 it is 1.84 kW.

Typical ranges only. Use the nameplate or a meter reading whenever you have one.

Which way you are converting changes what a cautious guess looks like. When you size a cable from kW to amps, assuming a lower power factor gives a higher current, so it errs on the safe side. When you turn measured amps into kW, a lower power factor gives a lower power, so assuming 1 would overstate it. If you honestly do not know the load, 0.8 is a reasonable guess for a motor and 0.95 suits mixed modern equipment.

Real-Life Examples

A few situations where the conversion actually earns its keep.

Home EV charger

A 32 A home charger on a 230 V single-phase supply delivers 230 x 32 / 1000 = 7.36 kW, since the power factor of a charger is very close to 1. That is where the common 7 kW charger rating comes from. To see what a full charge costs, put the kW figure into our EV charging cost calculator.

Workshop motor

A three-phase motor on a 400 V supply draws 20 A at a power factor of 0.85. Real power is 1.732 x 400 x 20 x 0.85 / 1000 = 11.78 kW of electrical input. The shaft will deliver less, because no motor is 100% efficient, so do not read that figure as mechanical output.

Battery bank

A 48 V battery system feeding an inverter at 100 A is moving 48 x 100 / 1000 = 4.8 kW on the DC side. The AC side will be a little lower once the inverter losses come off, so treat the DC figure as the upper limit.

Generator sizing

A 25 kW three-phase load at 400 V and a power factor of 0.8 draws 25000 / (1.732 x 400 x 0.8) = 45.11 A per line. The apparent power is 25 / 0.8 = 31.25 kVA, and generators are rated in kVA, which is why a 25 kW load needs a set bigger than 25 kVA. Leave extra room for motor start-up surges before you buy anything.

Long cable runs

Over a long run the voltage at the far end drops, and the load then draws more current for the same power. If that sounds like your setup, work out the drop first with our voltage calculator, then use the actual voltage at the load in this one.

Using it as a quick electrical load calculator

Do not add up amps from loads that run at different voltages or power factors. Convert each appliance to kW first, add the kW together, then switch to kW to A and enter the total with the one voltage the whole circuit runs on.

Common Mistakes to Avoid

• Skipping power factor. 10 A at 230 V is 2.3 kVA, not 2.3 kW, unless the power factor is 1.
• Mixing up line-to-line and line-to-neutral. Typing 230 into three-phase L-L mode understates the power by a factor of 1.732.
• Treating kVA as kW. Generator and transformer plates are usually in kVA. Multiply by the power factor to get kW.
• Forgetting start-up current. A motor can draw several times its running current for a moment when it starts. The formulas describe steady running only.
• Using peak values. Meters and nameplates quote RMS values, and the formulas expect RMS too.
• Assuming a balanced load. The three-phase formulas assume the same current in all three phases. If one phase is far busier, work each phase out separately.
• Ignoring efficiency. The kW you calculate is electrical input. A motor or inverter gives back less than it takes in.

Safety note. This calculator is for estimates, study and planning. For real installations follow your local wiring regulations, and have a qualified electrician confirm cable and protection sizes.

Amps, kW, kVA and Watts: What Is the Difference?

Because the Watts tile shows real power in W, you can use the calculator as an amps to watts calculator as well: 10 A at 230 V and PF 1 is 2300 W.

For kVA to amps, the sum is shorter because kVA already includes the power factor. Single-phase: amps = kVA x 1000 / volts. Three-phase: amps = kVA x 1000 / (1.732 x volts). So 31.25 kVA at 400 V three-phase is 45.11 A, the same answer as the generator example above.

kW is power, kWh is energy. Run a 2 kW heater for 3 hours and you have used 6 kWh. To put a price on that, use our electricity cost calculator. If a datasheet quotes energy in kilojoules instead, 1 kWh equals 3,600 kJ, and the kJ to Wh converter does the rest.

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