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Amps to kVA Calculator

Convert electrical current in amperes (A) to apparent power in kilovolt-amperes (kVA). Calculate kVA for single-phase and three-phase electrical systems.

Calculate kVA from Amps

Phase Type

Current (Amps)

Voltage (Volts)

Common voltages: 120V, 208V, 240V, 277V, 480V, 600V

Results:

Kilovolt-Amps (kVA)41.57

Volt-Amps (VA)41,569

Megavolt-Amps (MVA)0.0416

Amps to kVA Formulas

Single Phase

kVA = (A × V) ÷ 1000

kVA equals amps times volts divided by 1000

Three Phase

kVA = (√3 × A × V) ÷ 1000

√3 ≈ 1.732 for three-phase calculations

What is kVA?

kVA (kilovolt-ampere) is a unit of apparent power in an electrical circuit. It represents the total power flowing in a circuit, including both real power (kW) and reactive power (kVAR).

•kVA = Apparent Power (total power)
•kW = Real Power (useful power)
•kVAR = Reactive Power

What Is Amps to kVA Conversion?

Kilovolt-amperes (kVA) represent apparent power in an AC electrical system, combining both real power (kW) and reactive power (kVAR). Converting amps to kVA helps size transformers, generators, and UPS systems. The formula for single-phase is: kVA = (Amps × Volts) ÷ 1000. For three-phase: kVA = (Amps × Volts × √3) ÷ 1000. Unlike kW (which accounts for power factor), kVA represents the total electrical demand on the power source. Transformers and generators are rated in kVA because they must handle the total apparent power regardless of power factor.

How to Calculate Amps to kVA Conversion

1
Select Phase Configuration
Choose single-phase (residential, small commercial) or three-phase (industrial, large commercial). This determines whether the √3 (1.732) multiplier is applied.
2
Enter Current in Amps
Input the total current draw. For three-phase systems, enter the line current (not phase current). Use a clamp meter on the line conductor for accurate readings.
3
Enter System Voltage
Input line-to-line voltage for three-phase (208V, 480V, 600V) or line-to-neutral voltage for single-phase (120V, 240V). Verify voltage with a multimeter.
4
Read the kVA Result
The result shows the apparent power demand. Use this to size transformers (next standard size up), generators, and conductors per NEC requirements.

Why Amps to kVA Conversion Matters

Transformer Sizing

Transformers are rated in kVA, not kW. Converting load amps to kVA ensures proper transformer selection. An undersized transformer overheats and fails; oversized transformers waste capital and have higher no-load losses.

Generator Capacity Planning

Standby and prime power generators are rated in kVA. Accurate conversion from measured amps ensures the generator can handle the full apparent power demand, including reactive loads like motors and transformers.

Utility Billing and Demand Charges

Many commercial utility tariffs include demand charges based on kVA rather than kW. Understanding your kVA demand helps optimize power factor correction to reduce electricity costs.

UPS System Design

Uninterruptible power supplies are rated in kVA. Converting critical load amps to kVA ensures adequate UPS capacity with appropriate headroom for future expansion.

Electrical Safety Tips & Best Practices

Transformers Need Headroom

Size transformers at 80% of rated kVA for continuous loads. A 100 kVA transformer should serve no more than 80 kVA continuous load to prevent overheating and extend service life.

kVA vs kW Relationship

kW = kVA × Power Factor. A 100 kVA load at 0.85 power factor consumes 85 kW of real power. Improving power factor reduces kVA demand without reducing useful work output.

Measure All Phases

In three-phase systems, unbalanced loads cause different currents on each phase. Measure all three phases and use the highest current for conservative kVA sizing.

Include Future Load Growth

Design electrical systems with 20-25% spare capacity for future load growth. This prevents costly transformer upgrades when adding new equipment.

Single Phase Amps to kVA Conversion Chart

Amps (A)	kVA @ 120V	kVA @ 208V	kVA @ 240V	kVA @ 480V
10 A	1.2 kVA	2.08 kVA	2.4 kVA	4.8 kVA
20 A	2.4 kVA	4.16 kVA	4.8 kVA	9.6 kVA
30 A	3.6 kVA	6.24 kVA	7.2 kVA	14.4 kVA
50 A	6 kVA	10.4 kVA	12 kVA	24 kVA
100 A	12 kVA	20.8 kVA	24 kVA	48 kVA
200 A	24 kVA	41.6 kVA	48 kVA	96 kVA

Three Phase Amps to kVA Conversion Chart

Amps (A)	kVA @ 208V	kVA @ 240V	kVA @ 480V	kVA @ 600V
10 A	3.60 kVA	4.16 kVA	8.31 kVA	10.39 kVA
20 A	7.20 kVA	8.31 kVA	16.63 kVA	20.78 kVA
30 A	10.80 kVA	12.47 kVA	24.94 kVA	31.18 kVA
50 A	18.00 kVA	20.78 kVA	41.57 kVA	51.96 kVA
100 A	36.00 kVA	41.57 kVA	83.14 kVA	103.92 kVA
200 A	72.00 kVA	83.14 kVA	166.28 kVA	207.85 kVA

Frequently Asked Questions

What is the difference between kVA and kW?

kVA measures apparent power (total power), while kW measures real power (useful power). They are related by the power factor: kW = kVA × Power Factor. For resistive loads, kW equals kVA. For inductive loads like motors, kVA is higher than kW.

Why do generators and transformers use kVA ratings?

Generators and transformers are rated in kVA because their capacity is limited by the current they can carry without overheating, regardless of the power factor. The kVA rating indicates the maximum apparent power they can handle.

How do I size a generator using kVA?

Add up the total kVA of all loads you need to power. Add a 20-25% safety margin for motor starting currents and future expansion. Choose a generator with a kVA rating that exceeds your total calculated requirement.

How do I convert 100 amps to kVA?

For single-phase at 240V: kVA = (100 × 240) ÷ 1000 = 24 kVA. For three-phase at 480V: kVA = (100 × 480 × 1.732) ÷ 1000 = 83.1 kVA. The result depends on both the current and the system voltage.

Why are generators rated in kVA not kW?

Generators must supply the total apparent power (kVA) including reactive power for motors and transformers. The generator alternator and windings handle total current regardless of power factor. The kW rating depends on the prime mover (engine) capacity, which is typically 80% of kVA rating.

How do I size a transformer from amps?

Convert total load amps to kVA using the formula. Then select the next standard transformer size (e.g., 15, 25, 37.5, 50, 75, 100, 150, 225, 300, 500, 750, 1000 kVA). Apply an 80% loading factor — a 50 kVA transformer should serve no more than 40 kVA continuous.

What happens if kVA exceeds equipment rating?

Exceeding kVA ratings causes excessive current flow, leading to overheating of conductors, transformers, and switchgear. This can trigger protective devices (breakers/fuses), damage insulation, reduce equipment lifespan, and in severe cases cause electrical fires. Always size equipment above the calculated kVA demand.

Related Electrical Calculators

⚡kVA to Amps ⚡kVA to kW ⚡Amps to kW ⚡Amps to Watts

References & Industry Standards

NEC Article 450 - Transformers and Transformer Vaults
IEEE C57.12.00 - Standard for Liquid-Immersed Distribution Transformers
NEMA TP 1 - Guide for Determining Energy Efficiency for Distribution Transformers
IEC 60076 - Power Transformers Standards

Last updated: 2026-02-01 | Reviewed by UnitTables Engineering Team

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What Is Amps to kVA Conversion?

How to Calculate Amps to kVA Conversion

Select Phase Configuration

Choose single-phase (residential, small commercial) or three-phase (industrial, large commercial). This determines whether the √3 (1.732) multiplier is applied.

Enter Current in Amps

Input the total current draw. For three-phase systems, enter the line current (not phase current). Use a clamp meter on the line conductor for accurate readings.

Enter System Voltage

Input line-to-line voltage for three-phase (208V, 480V, 600V) or line-to-neutral voltage for single-phase (120V, 240V). Verify voltage with a multimeter.

Read the kVA Result

The result shows the apparent power demand. Use this to size transformers (next standard size up), generators, and conductors per NEC requirements.

Why Amps to kVA Conversion Matters

Transformer Sizing

Generator Capacity Planning

Utility Billing and Demand Charges

Many commercial utility tariffs include demand charges based on kVA rather than kW. Understanding your kVA demand helps optimize power factor correction to reduce electricity costs.

UPS System Design

Uninterruptible power supplies are rated in kVA. Converting critical load amps to kVA ensures adequate UPS capacity with appropriate headroom for future expansion.

Electrical Safety Tips & Best Practices

Transformers Need Headroom

Size transformers at 80% of rated kVA for continuous loads. A 100 kVA transformer should serve no more than 80 kVA continuous load to prevent overheating and extend service life.

kVA vs kW Relationship

kW = kVA × Power Factor. A 100 kVA load at 0.85 power factor consumes 85 kW of real power. Improving power factor reduces kVA demand without reducing useful work output.

Measure All Phases

In three-phase systems, unbalanced loads cause different currents on each phase. Measure all three phases and use the highest current for conservative kVA sizing.

Include Future Load Growth

Design electrical systems with 20-25% spare capacity for future load growth. This prevents costly transformer upgrades when adding new equipment.

Amps (A)

kVA @ 120V

kVA @ 208V

kVA @ 240V

kVA @ 480V

10 A

1.2 kVA

2.08 kVA

2.4 kVA

4.8 kVA

20 A

2.4 kVA

4.16 kVA

4.8 kVA

9.6 kVA

30 A

3.6 kVA

6.24 kVA

7.2 kVA

14.4 kVA

50 A

6 kVA

10.4 kVA

12 kVA

24 kVA

100 A

12 kVA

20.8 kVA

24 kVA

48 kVA

200 A

24 kVA

41.6 kVA

48 kVA

96 kVA

Amps (A)

kVA @ 208V

kVA @ 240V

kVA @ 480V

kVA @ 600V

10 A

3.60 kVA

4.16 kVA

8.31 kVA

10.39 kVA

20 A

7.20 kVA

8.31 kVA

16.63 kVA

20.78 kVA

30 A

10.80 kVA

12.47 kVA

24.94 kVA

31.18 kVA

50 A

18.00 kVA

20.78 kVA

41.57 kVA

51.96 kVA

100 A

36.00 kVA

41.57 kVA

83.14 kVA

103.92 kVA

200 A

72.00 kVA

83.14 kVA

166.28 kVA

207.85 kVA

Frequently Asked Questions

What is the difference between kVA and kW?

Why do generators and transformers use kVA ratings?

How do I size a generator using kVA?

How do I convert 100 amps to kVA?

For single-phase at 240V: kVA = (100 × 240) ÷ 1000 = 24 kVA. For three-phase at 480V: kVA = (100 × 480 × 1.732) ÷ 1000 = 83.1 kVA. The result depends on both the current and the system voltage.

Why are generators rated in kVA not kW?

How do I size a transformer from amps?

What happens if kVA exceeds equipment rating?

References & Industry Standards

NEC Article 450 - Transformers and Transformer Vaults

IEEE C57.12.00 - Standard for Liquid-Immersed Distribution Transformers

NEMA TP 1 - Guide for Determining Energy Efficiency for Distribution Transformers

IEC 60076 - Power Transformers Standards

Last updated: 2026-02-01 | Reviewed by UnitTables Engineering Team