This k va calculator takes the figures you already have and applies the relationship behind k va calculations for you, giving apparent power (s) and power factor from current (i), real power (p), real power (p), real power (p) and voltage (v).
What Is the K VA Calculator?
This k va calculator is for the kind of problem where you know the physical quantities but not the number you need. It turns current (i), real power (p), real power (p), real power (p) and voltage (v) into apparent power (s) and power factor.
Physics calculations go wrong in predictable ways, usually through mixing units or dropping a digit. Work through the result one step at a time and check that the figures are the size you would expect at each stage.
How the K VA Physics Works
The relationship is applied step by step, and each step is a standard piece of physics rather than a single opaque formula. That means you can check the intermediate values against what the theory predicts, which is usually faster than checking only the final answer.
Keep every value in the same unit system throughout the calculation. Mixing metres and feet part way through is the single most common reason a correct formula gives a wrong answer.
Units, Assumptions and the Limits of the Model
The calculation assumes ideal conditions: no air resistance, no heat loss, and dimensions that do not change while you work. Those assumptions are reasonable for most classroom and engineering estimates, and unreasonable for anything more precise.
Where a value is a rate, it has to be quoted for the same period as everything else. A per-hour figure cannot be combined with a per-day figure without converting one of them first.
A Worked Example
Working through an example, with current (i) set to 10, real power (p) set to 5, real power (p) set to 2, the calculator returns apparent power (s) of 0.1, and power factor of 50, and apparent power (s) (kva3 pll) of 0.17321. Substitute your own figures and the same steps produce the same kind of answer.
Frequently Asked Questions
What do I need to work out apparent power (s)?
Enter current (i), real power (p), real power (p), real power (p) and voltage (v). The calculator then works through the relationship and reports apparent power (s) and power factor.
What does the k va actually calculate?
It takes current (i), real power (p), real power (p), real power (p) and voltage (v) and converts them into apparent power (s) and power factor using the standard relationship for this problem. Each step is applied in turn, so every output is traceable back to the numbers you typed in.
How should I enter current (i)?
Use the value you actually have, in the unit shown next to the field. Enter every value in the same unit system. The calculator assumes the figures you supply are consistent, so it cannot correct a mistake that happens before the calculation starts.
Why does a small change in one value move the answer so much?
That happens when an output depends on a ratio, because dividing by a small number magnifies any change in it. Check the units first, then check whether the value you entered is in the range the relationship was designed for.
Does anything you type get stored?
No. The whole calculation runs inside your browser, and nothing you enter is uploaded, logged or sent anywhere.