kW to kVA Converter
Convert real power in kW to apparent power in kVA for sizing generators and transformers.
What this tool does
A kW to kVA converter divides real power by the power factor: kVA = kW ÷ PF. Real power in kW is what your loads consume; apparent power in kVA is what the supply, cable and transformer must be rated to deliver. Eight kilowatts at a power factor of 0.8 needs 10 kVA of equipment.
Converts real power in kW into apparent power in kVA using the power factor.
Shows the formula used with the result, so the division can be checked by hand.
Explains why kVA always equals or exceeds kW, and by how much for common loads.
Updates instantly as you change the load or the power factor.
How to use it
- Enter the real power of your loads in kW.
- Enter the power factor - 0.8 is the conventional default when unknown.
- Read the apparent power in kVA.
- Add headroom and check the surge rating before choosing equipment.
Why use this calculator
Converts real power in kW into apparent power in kVA using the power factor, which is the step most people skip when buying a generator. Loads are described in kilowatts, but generators, transformers and UPS units are sold in kilovolt-amps - and dividing by a power factor below one is what stops an apparently adequate unit from tripping the moment it carries real equipment.
Why we built it
We built the kW to kVA converter for the sizing direction, where a known load has to become an equipment rating. The kVA to kW converter reverses it when you are reading what a rating plate actually delivers, the Power Factor Calculator finds the power factor from measurements, and the solar inverter size calculator applies the same arithmetic to a solar system.
If your task goes further, try the watts to amps converter for cable and breaker sizing, the amps to watts converter for the load side, and the volts to watts calculator for the base calculation.
Who this tool is for
- Anyone specifying a generator, transformer or UPS from a load list
- Electricians preparing a schedule of loads for a supply application
- Facilities teams responding to demand or power factor charges
- Students working between real and apparent power
When to use it
- Sizing a generator in kVA from loads measured in kW.
- Checking a transformer or UPS quote against your demand.
- Preparing a load schedule for a new installation.
- Estimating the apparent power behind a demand charge.
How it is calculated
Apparent power in kVA = real power in kW ÷ power factor. The power factor sits in the denominator because it is the fraction of apparent power that becomes real power, so to recover the whole you divide rather than multiply. Worked example: 8 kW ÷ 0.8 = 10 kVA. On a three-phase system the same kVA can be turned into line current with the supply voltage, which is where cable sizing picks up.
Generator sizing goes one step further than this division. Take the total running kW of everything that can be on together, divide by the power factor, then add margin for starting surges - motors and compressors can draw two to five times their running current for a moment. A 6 kW load at 0.85 needs 7.1 kVA continuous, and choosing an 8 to 10 kVA unit leaves room for both the margin and the startup.
kVA can equal kW but can never be lower: the power factor cannot exceed 1. A figure claiming more kW than kVA has mixed the units or assumed an impossible power factor.
What you enter, and what you get back
| Item | Details |
|---|---|
| Real power | The load in kilowatts. |
| Power factor | 0 to 1; 0.8 is the usual default. |
| Result | Apparent power in kVA, with the formula used. |
| Reference | Typical power factor values for common loads. |
A worked example
A worked example you can repeat in the calculator above. Change the load or the power factor and the required kVA updates from the same division.
| Input | Value |
|---|---|
| Real power | 8 kW |
| Power factor | 0.8 |
With those inputs, the calculator returns:
- Apparent power: 10 kVA
- Formula used: kVA = kW ÷ PF = 8 ÷ 0.8
- At 0.95 the same load would need 8.4 kVA
- Reactive power behind it: 6 kVAR
Sizing a generator in kVA
List every load that runs simultaneously, add their running watts and divide by 1,000 for kW, then convert to kVA here. Round up, add 20% to 25% headroom, and confirm the surge rating covers the largest motor. Resistive loads - heaters, lighting, ovens - sit near 1.0, so a purely resistive site needs almost no conversion; a workshop full of motors needs far more.
| Load | Running power | Note |
|---|---|---|
| Lighting circuit | 1.2 kW | Mostly resistive, PF near 1.0 |
| Workshop tools | 2.4 kW | Motor loads, PF around 0.8 |
| Office equipment | 1.0 kW | Switch-mode supplies, PF 0.7 to 0.9 |
| Kitchen appliances | 1.4 kW | Mixed resistive and motor |
| Total | 6.0 kW | Blended PF taken as 0.85 |
| Required | 7.1 kVA | Plus surge - choose 8 to 10 kVA |
Generators are happiest between 50% and 75% of their rated load, so the 20% to 25% margin improves fuel efficiency as well as protecting against trips.
Issues you may run into
| What you see | Why it happens | What to do |
|---|---|---|
| Equipment seems oversized | A low power factor was assumed for resistive loads. | Match the power factor to the actual load type. |
| Unit trips under load | Only running kW was converted; surge was ignored. | Check the surge rating for motor starts. |
| Result below the kW figure | Power factor entered above 1 or units mixed. | Use a power factor between 0 and 1. |
| Bill shows a penalty | Supply power factor below the tariff threshold. | Use the power factor calculator to size correction. |
Assumptions and limitations
- A single-point conversion; it does not model starting surges, harmonics or equipment derating curves.
- The power factor you enter drives the answer - an assumed 0.8 may be optimistic for lightly loaded motors.
- Covers apparent power only; cable current requires the supply voltage and, for three-phase, the √3 factor.
- An aid for estimation, not a design for a live installation.
Frequently asked questions
How do I convert kW to kVA?
Divide the kilowatts by the power factor: kVA = kW ÷ PF. Eight kW at a power factor of 0.8 needs 10 kVA, at 0.9 it needs 8.9 kVA, and at 1.0 the two figures match. Use 0.8 when the true power factor is unknown and the load is mixed.
What is the difference between kW and kVA?
kW is real power - the electricity your equipment converts into heat, light or motion, and the figure your bill charges for. kVA is apparent power - the total the supply must deliver, including the reactive part that flows back and forth. Equipment is rated in kVA because its limits are set by current.
Why is kVA always higher than kW?
Because apparent power includes both real and reactive power. Reactive power sustains the magnetic fields in motors and transformers and returns to the supply each cycle, but it still flows through every conductor. Dividing kW by a power factor of 1.0 or less therefore always gives a kVA figure that is equal to or larger than the kW.
What is power factor?
Real power divided by apparent power, expressed between 0 and 1. It is also the cosine of the angle by which current lags or leads voltage. Motors, transformers and inductive loads pull it down; power factor correction capacitors push it back up. Tariffs on commercial supplies often require 0.9 or better.
How do I size a generator in kVA?
Add the running watts of all simultaneous loads, divide by 1,000 for kW, convert to kVA with this calculator, then add 20% to 25% headroom and confirm the surge rating covers the largest motor's start. A 6 kW mixed load at 0.85 is 7.1 kVA, which points to an 8 to 10 kVA generator.
How do I convert kVA to kW?
Multiply the kVA by the power factor: kW = kVA × PF. Ten kVA at 0.8 delivers 8 kW of usable power. The kVA to kW converter on this site runs that direction when you need to know what a rating plate actually gives you.