# How to calculate kVAR from kW? Step-by-Step Calculation with Formula

**URL:** <https://forumautomation.com/t/how-to-calculate-kvar-from-kw-step-by-step-calculation-with-formula/14298>\
**Category:** Electrical\
**Tags:** calculator\
**Created:** [August 5, 2026, 11:27am UTC](https://forumautomation.com/t/how-to-calculate-kvar-from-kw-step-by-step-calculation-with-formula/14298 "2026-08-05T11:27:29Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![Rabert](https://forumautomation.com/user_avatar/forumautomation.com/rabert/32/6784_2.png) [@Rabert](https://forumautomation.com/u/Rabert)\
**Post date:** [August 5, 2026, 11:27am UTC](https://forumautomation.com/t/how-to-calculate-kvar-from-kw-step-by-step-calculation-with-formula/14298/1 "2026-08-05T11:27:29Z")

</div>

**[Reactive power (kVAR)](https://forumelectrical.com/what-is-the-difference-between-kw-and-kva/)** can be calculated from active power ( **kW** ) using the power factor of the electrical system. This calculation is essential for capacitor bank sizing, power factor correction, and electrical system design.

## **Formula to Calculate kVAR**

kVAR = kW x tan(cos−1(Power Factor))​

Where:

- **kW** = Active Power
- **Power Factor (PF)** = Decimal value (e.g., 0.8, 0.9, 0.95)
- **kVAR** = Reactive Power

## **Step-by-Step Calculation**

**Given:**

- Active Power = **100 kW**
- Power Factor = **0.80**

**Step 1:** Find the phase angle

Θ = cos−1(0.80) = 36.87∘

**Step 2:** Calculate tan θ

tan(36.87∘) = 0.75

**Step 3:** Calculate reactive power

kVAR = 100 x 0.75 = 75 kVAR

**Answer:**  **Reactive Power = 75 kVAR**

## **Why Calculate kVAR?**

- Size capacitor banks correctly
- Improve power factor
- Reduce reactive power penalties
- Improve system efficiency
- Optimize transformer and generator loading
- Minimize power losses in electrical networks ![1 - Copy](https://cdn.forumautomation.com/original/2X/1/1979c9570f4657df78f510ab3bd1b67ab14316b2.jpeg)

## Calculators

### [kW to kVA Calculator for Diesel Generators](https://forumelectrical.com/kw-to-kva-calculator-for-diesel-generators/)

### [KW TO KVA CALCULATOR](https://forumelectrical.com/kw-to-kva-calculator/)

### [kVA/kW Ampere (Amp) Chart](https://forumelectrical.com/kva-kw-ampere-amp-chart/)

## **Applications**

- Industrial power systems
- Electrical distribution networks
- Motor installations
- Transformer sizing
- Power factor correction projects
- Solar and renewable energy systems
- Electrical energy audits