1 kW ÷ PF × 1,000. At PF 1.0 it is 1,000 VA; at PF 0.9, 1,111 VA; at PF 0.8, 1,250 VA.

kW to VA Calculator

Q: What size UPS do I need for 1,000 watts?

Divide by the UPS power factor rating and add headroom. At PF 0.9, 1,000 W needs at least 1,111 VA; a 1,500 VA unit gives comfortable margin. Also confirm the UPS's watt rating is at least 1,000 W.

Q: Why is VA higher than watts?

Because VA includes reactive power, which flows in the circuit without doing useful work. Only at a power factor of 1.0 are VA and watts equal.

Q: What power factor should I use?

Use the value from the equipment's datasheet if you have it. Otherwise, 0.8 is a common conservative assumption for mixed loads, 0.9–0.99 for modern IT equipment and 1.0 for purely resistive heating.

Convert kilowatts (kW) to volt-amps (VA) using power factor: VA = kW × 1,000 ÷ PF. Size a UPS, inverter or transformer for a known real-power load.

⚡ REAL POWER

📊 POWER FACTOR

APPARENT POWER

5,882 VA

IN kVA

5.88 kVA

FORMULA

VA = (kW×1000)/PF

POWER FACTOR

0.85

💡 How to Convert kW to VA

To convert kW to VA, multiply the kilowatts by 1,000 and divide by the power factor. Because the power factor is 1 or less, the VA figure is always equal to or larger than the watt figure. That larger number is what your UPS, inverter or transformer must be rated for.

kW to VA formula

VA = kW × 1,000 ÷ PF

Example: 5 kW at PF 0.85 → 5 × 1,000 ÷ 0.85 = 5,882 VA

Worked examples

Sizing a UPS for a server rack: 0.9 kW of servers with PFC power supplies (PF 0.9) needs at least 1,000 VA. With 25% headroom, choose about 1,250 VA.
Workshop machinery (PF 0.8): 3 kW ÷ 0.8 = 3,750 VA.
Resistive heater (PF 1.0): 2 kW = 2,000 VA; with no reactive power, VA equals watts.

kW to VA table at common power factors

kW	VA @ PF 0.6	VA @ PF 0.8	VA @ PF 0.9	VA @ PF 1.0
0.5	833	625	556	500
0.9	1,500	1,125	1,000	900
1	1,667	1,250	1,111	1,000
1.5	2,500	1,875	1,667	1,500
2	3,333	2,500	2,222	2,000
3	5,000	3,750	3,333	3,000
5	8,333	6,250	5,556	5,000
10	16,667	12,500	11,111	10,000
20	33,333	25,000	22,222	20,000
50	83,333	62,500	55,556	50,000

Typical power factors: resistive loads such as heaters and incandescent lamps run at 1.0; computer and server power supplies with power factor correction (PFC) run at about 0.95–0.99; induction motors run at roughly 0.8–0.9 at full load and lower when lightly loaded. Diesel generators are conventionally rated at a power factor of 0.8.

Why a lower power factor means a bigger rating

A load with a low power factor draws more current for the same useful work. That extra current heats cables and windings even though it does no work, so equipment has to be rated for the full apparent power. Improving power factor (for example, with capacitor banks on large motor installations) reduces the VA you need.

Related conversions: VA to kW · kW to kVA · watts to kVA

VA = kW × 1,000 ÷ power factor. 5 kW at PF 0.85 needs 5,882 VA of capacity.