# Amps to Kilovolt-Amps (kVA) Converter

> Convert electrical current (amps) to apparent power in kilovolt-amps (kVA) for single-phase and three-phase AC circuits

**Category:** Conversion
**Keywords:** amps, kva, kilovolt-amps, apparent power, electrical, current, ac, three phase, single phase, transformer, generator
**URL:** https://complete.tools/amps-to-kva-converter

## How it calculates

The calculation method depends on whether you are working with a single-phase or three-phase electrical system:

**Single-Phase AC Circuits:**
The formula is: kVA = (Amps × Volts) / 1000. This straightforward calculation multiplies the current in amperes by the voltage in volts, then divides by 1000 to convert volt-amps (VA) to kilovolt-amps (kVA). For example, a 30-amp circuit at 240 volts would have an apparent power of (30 × 240) / 1000 = 7.2 kVA.

**Three-Phase AC Circuits:**
For three-phase systems, the formula becomes: kVA = (Amps × Volts × √3) / 1000. The √3 factor (approximately 1.732) is essential because three-phase power involves three alternating currents that are offset by 120 degrees from each other. This phase relationship means the total power delivered is greater than simply multiplying voltage by current. When using line-to-line voltage (the voltage measured between any two phases), the √3 multiplier correctly calculates the total apparent power. For instance, a 50-amp three-phase load at 480 volts calculates as (50 × 480 × 1.732) / 1000 = 41.57 kVA.

**Important Note:** This calculator determines apparent power (kVA), not real power (kW). To convert kVA to kW, multiply by the power factor: kW = kVA × PF. For equipment sizing purposes, kVA is typically the more important specification.

## Who should use this

Electrical engineers designing power distribution systems rely on kVA calculations when specifying transformers and switchgear. A transformer must be sized to handle the full apparent power of connected loads, making kVA the primary sizing criterion. Facility managers and building engineers use this calculator when assessing electrical capacity for new equipment installations or evaluating whether existing infrastructure can support additional loads. Generator sizing requires accurate kVA calculations because generators must supply the full apparent power, including reactive power components that motors and other inductive loads demand. HVAC contractors calculate the kVA requirements of air conditioning equipment to ensure adequate electrical supply. Data center operators use kVA ratings extensively because UPS systems and power distribution units (PDUs) are typically rated in kVA. Electricians working on commercial and industrial projects frequently convert between amps and kVA when interpreting equipment nameplates and sizing conductors. Solar installers and renewable energy professionals use these calculations when determining inverter capacity and grid connection requirements.

## Worked examples

Example 1 (Residential Single-Phase): A homeowner wants to know the kVA demand of their 200-amp main electrical panel at 240 volts. Using the single-phase formula: kVA = (200 A × 240 V) / 1000 = 48 kVA. This represents the maximum apparent power capacity of the panel.

Example 2 (Commercial Single-Phase): An office server room draws 15 amps at 208 volts. The apparent power requirement is: kVA = (15 A × 208 V) / 1000 = 3.12 kVA. A 5 kVA UPS would provide adequate capacity with room for growth.

Example 3 (Industrial Three-Phase): A manufacturing facility has a motor that draws 100 amps per phase at 480 volts. Using the three-phase formula: kVA = (100 A × 480 V × 1.732) / 1000 = 83.14 kVA. The facility would need a transformer rated at least 100 kVA to serve this motor with safety margin.

Example 4 (Generator Sizing): A small business needs backup power for equipment drawing a total of 75 amps on a three-phase 208-volt system. Calculation: kVA = (75 A × 208 V × 1.732) / 1000 = 27.01 kVA. They would typically choose a 30 kVA or larger generator to ensure reliable operation.

Example 5 (Transformer Selection): An electrician needs to size a transformer for a three-phase load drawing 30 amps at 600 volts. The calculation shows: kVA = (30 A × 600 V × 1.732) / 1000 = 31.18 kVA. Standard transformer sizes being 30, 45, and 75 kVA, the electrician would select a 45 kVA transformer.

## Understanding kVA ratings

Kilovolt-amps (kVA) is the standard unit for rating electrical equipment capacity, particularly transformers, generators, and UPS systems. Unlike kW, which only measures real power doing useful work, kVA represents the total power that equipment must handle, including reactive power from inductive and capacitive loads. This is why a 10 kVA transformer is not the same as a 10 kW transformer. If connected loads have a power factor of 0.8, that 10 kVA transformer can only deliver 8 kW of real power (10 kVA × 0.8 = 8 kW). Equipment manufacturers specify kVA ratings because the equipment must carry the full current regardless of power factor. Wire and cable sizing also relates to apparent power because conductors must carry the full current even when some of that current does not perform useful work. Understanding this distinction prevents undersizing equipment, which can lead to overheating, reduced equipment life, and potential safety hazards. When evaluating existing electrical systems or planning new installations, always verify both the kVA capacity and the expected power factor of loads to ensure adequate real power is available.

## Limitations

This calculator provides apparent power calculations for steady-state conditions. Real-world electrical systems may experience transient conditions such as motor starting currents that temporarily exceed steady-state values by 6 to 8 times. When sizing equipment, these inrush currents must be considered separately. The calculator assumes balanced three-phase loads where each phase carries equal current. Unbalanced loads require individual phase calculations and may result in higher neutral currents. Voltage values should represent actual operating conditions; nominal voltage ratings may differ from measured values, affecting calculation accuracy. The calculator does not account for harmonics, which can increase apparent power requirements in systems with non-linear loads like variable frequency drives or LED lighting with poor power factor correction. For critical applications, consultation with a licensed electrical engineer is recommended to account for all factors affecting equipment sizing including ambient temperature, altitude, and specific equipment derating requirements.

## FAQs

**Q:** Why do transformers use kVA ratings instead of kW?


**A:** Transformers must carry the full current regardless of whether that current performs useful work. A purely reactive load (power factor of 0) draws current but performs no real work, yet the transformer still heats up from carrying that current. kVA ratings ensure transformers are sized for the actual current they must handle.


**Q:** How do I convert kVA to kW?


**A:** Multiply kVA by the power factor: kW = kVA × PF. For example, 10 kVA with a power factor of 0.85 equals 8.5 kW of real power. Without knowing the power factor, you cannot accurately convert between these units.


**Q:** What voltage should I use for three-phase calculations?


**A:** Use line-to-line voltage (measured between any two phases) with this calculator. Common three-phase voltages include 208V, 480V, and 600V. The √3 factor in the formula is appropriate for line-to-line voltage.


**Q:** Is kVA the same as VA?


**A:** Yes, they measure the same thing at different scales. 1 kVA equals 1,000 VA. Small equipment like computer UPS units often use VA ratings, while larger equipment uses kVA.


**Q:** Can I use this calculator for DC circuits?


**A:** DC circuits do not have reactive power, so kVA and kW are equivalent. For DC, simply calculate: kW = (Amps × Volts) / 1000. The concept of apparent power only applies to AC systems.


**Q:** What is a typical power factor for commercial buildings?


**A:** Commercial buildings typically have power factors between 0.80 and 0.95. Buildings with many motors (HVAC, elevators) tend toward the lower end, while those with mostly resistive loads (heating, lighting) are higher. Many utilities require power factor correction if it falls below 0.90.

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