Amp to VA Calculator
This calculator converts current in Amperes (A) to apparent power in Volt-Amps (VA), based on the system voltage. It's commonly used in sizing electrical systems, UPS units, transformers, and generators.
Why Convert Amps to VA?
When dealing with electrical systems, especially in AC power scenarios like UPS systems, generators, or building load planning, we often encounter current ratings (in amps) and apparent power ratings (in VA). Converting from amps to VA helps determine how much capacity a power source or circuit needs to safely and effectively handle the electrical load.
Volt-Amps (VA) represent apparent power, which includes both real power (watts) and reactive power (VARs). Apparent power is important in AC circuits because it reflects the total "burden" the power source sees, regardless of how much is actually converted into usable work.
Formula for Amps to VA
VA = Amps × Volts
This simple formula assumes a power factor (PF) of 1. In real-world AC systems, if you know the power factor:
VA = Watts / PF
However, for typical applications, converting directly using VA = A × V is sufficient for UPS and breaker sizing.
Example Calculations
- Example 1: 5 Amps at 120V → VA = 5 × 120 = 600 VA
- Example 2: 8.3 Amps at 240V → VA = 8.3 × 240 = 1992 VA
When to Use This Conversion
- Sizing UPS capacity for server rooms or home electronics
- Estimating how much current a given VA rating will draw at a specified voltage
- Designing or upgrading electrical panels and circuits
- Selecting transformers or backup generators
AC vs DC Systems
In DC systems, VA = W (watts) because power is purely real. In AC systems, VA includes both real and reactive power. That’s why UPS manufacturers often rate equipment in VA, as it includes total demand on the system.
Important Note:
In real AC circuits, if you want to estimate real power in watts, you need the power factor:
Watts = VA × PF
Common Amp to VA Chart (Assuming PF = 1)
| Current (A) | Voltage (V) | Apparent Power (VA) |
|---|---|---|
| 2 A | 120 V | 240 VA |
| 5 A | 208 V | 1040 VA |
| 10 A | 240 V | 2400 VA |
| 15 A | 230 V | 3450 VA |
| 20 A | 120 V | 2400 VA |
FAQs
Is VA the same as Watts?
No. VA is apparent power; Watts is real power. In AC circuits, they can differ due to power factor.
Can I use this for 3-phase systems?
This calculator is for single-phase systems. For 3-phase, the formula becomes: VA = √3 × Volts × Amps
What voltage should I enter?
Enter the voltage your equipment operates at — common values are 120V, 208V, 230V, or 240V depending on country and system type.
Do I need the power factor?
Only if you're calculating real power (Watts). For basic sizing in VA, power factor is not needed.
Conclusion
Converting amps to VA helps bridge the gap between current requirements and power capacity in any electrical setup. Whether you're sizing UPS systems, checking if a circuit is overloaded, or estimating generator needs, this simple conversion is crucial. This calculator offers a fast, reliable way to determine apparent power from a known current and voltage.