Skip to content
BuildWire Calc
All tools

Power

Wire & cable

Conduit & loads

Motors & gensets

kVA to kW Calculator

Multiply kVA by the power factor to get kW, or go back from kW to kVA, and see the kvar on a power triangle.

Free · runs in your browser · nothing is uploaded

Open on BuildWire Calc

This embed was switched off for this website. Open on BuildWire Calc

Add this tool to your siteFree embed code, no sign-up. Keep the credit link.

Embed this tool

Copy this code into your website, blog or class page. The tool runs inside your page.

Optional settings, added to the address after embed=1: &accent=0f6b5c (colour, 3 or 6 hex digits). Other parameters are ignored.

Please keep the credit link below the tool.

kVA to kW is one multiplication: kilowatts equal kilovolt-amperes times the power factor, so 100 kVA at a power factor of 0.8 is 80 kW. Enter the kVA and the power factor and the real power appears at once, together with the reactive power in kvar and the phase angle. A power triangle is drawn for your numbers, so you can see how the three quantities fit together. Switch Convert to “kW to kVA” when you know the real power and need the apparent power, for example to size a generator or transformer. A table under the result shows the kW and kvar of the same kVA at seven power factors from 0.7 to 1.
Kva to kw example

How to use the kVA to kW Calculator

  1. In Convert, keep “kVA to kW”, or choose “kW to kVA” to work the other way.
  2. Type the value into Apparent power (kVA), such as a generator or transformer rating. In the reverse mode this box becomes Real power (kW).
  3. Enter the Power factor (PF), a number above 0 and no more than 1. Use the nameplate or a measured value when you have one; the example values are planning figures only.
  4. Read Real power (P), or Apparent power (S) in the reverse mode.
  5. Check Reactive power (Q) and Phase angle (φ), and look at the power triangle drawn beside the result.
  6. Open “How it was calculated” to see each step, for example P = 100 kVA × 0.8 = 80 kW, Q = 60 kvar and φ = 36.87°.
  7. Read any warning. A power factor of 1 brings a note that kW then equals kVA, and a value below 0.5 is flagged as unusually low.

Four example buttons load common cases, such as “100 kVA at PF 0.85 (typical for motor loads)” and “12 kW at PF 0.6 (low power factor example)”. “Copy result” and “Copy link” copy the figures or a link with your inputs, “Print / save as PDF” prints them, and Reset restores the defaults.

Changing any field updates the result rows, the steps and the tables straight away, and Copy link keeps your exact inputs in the address so you can share or reopen the calculation.

How do I convert kVA to kW?

Real power is the apparent power scaled by how well the load uses it, so kW = kVA × PF. Because the power factor is never more than 1, the kW figure is never larger than the kVA. To go back, divide: kVA = kW ÷ PF. A 500 kVA rating with a power factor of 0.9 gives 450 kW.

  1. Take the kVA from the rating plate or the load you must supply.
  2. Find the power factor, ideally from a nameplate or a meter reading.
  3. Multiply: 100 kVA × 0.8 = 80 kW.
  4. In reverse, divide: a 45 kW load at 0.85 needs 45 ÷ 0.85 = 52.94 kVA.

The table under the result shows how much the power factor changes the answer for 100 kVA:

Power factorReal power (kW)Reactive power (kvar)
0.77071.41
0.88060
0.858552.68
0.99043.59
0.959531.22
11000

What is the difference between kVA and kW?

kVA is apparent power: volts times amps, the total the supply and cables must carry. kW is real power, the part that becomes heat, light or shaft work. The ratio kW ÷ kVA is the power factor. Equipment such as generators and transformers is rated in kVA, because its current limit depends on kVA and not on kW.

The difference is reactive power, measured in kvar. Motors and transformers need it to build their magnetic fields, and it flows back and forth without doing work. The three values form a right triangle, with kVA as the long side: S² = P² + Q².

What is reactive power (kvar)?

Reactive power is the side of the power triangle that does no real work: Q = √(kVA² − kW²). For 100 kVA at PF 0.8 it is √(100² − 80²) = 60 kvar. The phase angle between voltage and current, arccos(0.8) = 36.87°, describes the same triangle in degrees.

A lower power factor means a steeper triangle. At 0.6 the angle is 53.13°, and 12 kW of real power comes with 16 kvar of reactive power. Raising the power factor with capacitors shrinks the kvar side, which is what power factor correction does.

Worked examples

InputResult
100 kVA, PF 0.880 kW
500 kVA, PF 0.9450 kW
45 kW, PF 0.8552.94 kVA
120 kW, PF 0.95126.3 kVA

Calculated by the tool above; open it with the same values to see each step.

Questions, briefly answered

How many kW is 1 kVA?

One kVA equals 1 kW only at a power factor of 1. At PF 0.8, 1 kVA is 0.8 kW.

What is 20 kVA in kW?

With a power factor of 0.8, 20 kVA is 16 kW; with 0.9 it is 18 kW. Enter the power factor of your own load for an exact figure.

How many kVA are in 1 kW?

You need 1 ÷ PF kVA for each kW. At PF 0.8 that is 1.25 kVA, along with 0.75 kvar of reactive power.

Can kVA and kW be the same?

Yes, when the power factor is 1, as with a purely resistive heater. The tool then shows 0 kvar and a note that kW equals kVA.

Why does a low power factor need a bigger kVA rating?

The same real power needs more apparent power. With “kW to kVA”, a 12 kW load with a power factor of 0.6 needs 20 kVA and carries 16 kvar, while the same 12 kW at 0.95 needs only 12.63 kVA.

What power factor should I enter?

Use the value on the nameplate or a measured one. The example buttons carry planning values, such as 0.85 for motor loads and 0.9 for mixed loads, which you can edit.

Why does the tool reject a power factor above 1?

Real power can never exceed apparent power, so the power factor must be greater than 0 and no more than 1. Any other value returns an error instead of a result.