What is the formula for watts to kVA?

The formula is: S(kVA) = P(W) / (PF × 1000). Divide the real power in watts by the power factor and then by 1000 to get kilovolt-amperes.

What is a power factor?

Power factor (PF) is the ratio of real power (watts) to apparent power (VA). It ranges from 0 to 1. A PF of 1 means all power does useful work (purely resistive load). Inductive loads such as motors typically have a PF between 0.7 and 0.95.

What is the difference between watts and kVA?

Watts (W) measure real power — the power that actually performs work. kVA measures apparent power — the total power drawn from the source including reactive power. They are related by: kW = kVA × PF.

What power factor should I use if I do not know it?

If the power factor is unknown, a common conservative assumption is 0.8 for mixed industrial loads or 0.9 for modern electronic equipment. Always verify from the equipment nameplate or specification sheet when accuracy is critical.

Can this calculator be used for DC circuits?

No. kVA is an AC concept only. DC circuits have no reactive power or phase angle, so apparent power equals real power. For DC, simply divide watts by 1000 to get kilowatts (kW).

Why is kVA greater than or equal to kW?

Because the power factor is always between 0 and 1, dividing watts by PF always yields a value equal to or greater than the original watts (when expressed in kW). A lower power factor means a larger gap between kVA and kW.

Watts to kVA Calculator

Enter power in watts and a power factor to instantly convert to kilovolt-amperes (kVA).

Input Values

Real Power (W)

Power Factor (0.01 – 1.00)

Result

Enter values and press Calculate

Formula Reference

Watts to kVA

kVA = W / (PF × 1000)

PF = power factor (0.01 – 1.00)

Equivalent forms

kVA = kW / PF

kW = kVA × PF

Result copied!

Summary

This calculator converts real power in watts (W) to apparent power in kilovolt-amperes (kVA) using a user-supplied power factor. The power factor (0 to 1) accounts for the phase difference between voltage and current in AC circuits. The formula is: kVA = W / (PF × 1000). It is useful for sizing generators, transformers, and UPS systems when only the real power consumption and power factor are known.

How it works

Enter the real power in watts (W).
Enter the power factor (a value between 0.01 and 1).
Click Calculate to apply the formula kVA = W / (PF × 1000).
The result is displayed in kilovolt-amperes (kVA).
A breakdown table shows inputs, formula, and intermediate values.
Press Reset to clear all fields and start over.

Use cases

Size a generator or UPS when load wattage and power factor are known.
Determine transformer kVA rating for an industrial load.
Convert equipment real power consumption to apparent power for billing purposes.
Verify that an existing power source can handle a new load.
Plan electrical service capacity for data centers and server rooms.
Calculate kVA demand for HVAC systems with known PF.
Compare apparent power of loads with different power factors.
Cross-check nameplate wattage against the kVA rating on a supply unit.

Frequently Asked Questions

Last updated: 2026-05-23 · Reviewed by Nham Vu