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What is a volt-ampere?

AC apparent power — equals watts only for resistive loads

Definition

The volt-ampere equals one watt for purely resistive loads, but differs from watts for inductive or capacitive AC loads. Used for transformer, UPS and generator sizing — which must handle apparent power, not just real power.

Common uses

  • Transformer sizing
  • Uninterruptible power supply (UPS) ratings
  • Generator capacity

🌍 Real-world scale

Home UPS: 600–1500 VA. Transformer: kVA ratings. Motor power factor typically 0.8 — 1 kW motor = 1.25 kVA.

Convert from volt-amperes

7 conversions
Volt-Ampere to Watt1 VA = 1 WVolt-Ampere to Kilowatt1 VA = 0.001 kWVolt-Ampere to Megawatt1 VA = 1.0000e-6 MWVolt-Ampere to Mechanical Horsepower1 VA = 0.001341 hpVolt-Ampere to Metric Horsepower1 VA = 0.00136 PSVolt-Ampere to BTU per Hour1 VA = 3.41214 BTU/hVolt-Ampere to Foot-Pound per Second1 VA = 0.7376 ft·lbf/s

Convert to volt-amperes

7 conversions
Watt to Volt-Ampere1 W = 1 VAKilowatt to Volt-Ampere1 kW = 1,000 VAMegawatt to Volt-Ampere1 MW = 1,000,000 VAMechanical Horsepower to Volt-Ampere1 hp = 745.7 VAMetric Horsepower to Volt-Ampere1 PS = 735.499 VABTU per Hour to Volt-Ampere1 BTU/h = 0.2931 VAFoot-Pound per Second to Volt-Ampere1 ft·lbf/s = 1.35582 VA

Tips

  • VA = V × A (RMS).
  • For purely resistive loads, VA = W.
  • For motors, computers: VA > W (power factor < 1).

Common mistakes

  • Treating VA and W as identical — only true for resistive loads.
  • Buying UPS by W when VA rating is required.
  • Ignoring power factor in transformer sizing.

FAQ about the volt-ampere

What is a volt-ampere?
The volt-ampere equals one watt for purely resistive loads, but differs from watts for inductive or capacitive AC loads. Used for transformer, UPS and generator sizing — which must handle apparent power, not just real power.
Where is the volt-ampere used?
The volt-ampere is commonly used for: Transformer sizing; Uninterruptible power supply (UPS) ratings; Generator capacity.
What is an example of a volt-ampere in real life?
Home UPS: 600–1500 VA. Transformer: kVA ratings. Motor power factor typically 0.8 — 1 kW motor = 1.25 kVA.
What category does the volt-ampere belong to?
The volt-ampere is a unit of power, part of the 8-unit power category on UnitConv.
How accurate are volt-ampere conversions?
All conversion factors follow NIST and BIPM international standards to 8 significant figures — the highest practical accuracy.
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