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Amps to Kilowatts Calculator

Convert electrical current in amperes (A) to power in kilowatts (kW) for DC, single-phase AC, and three-phase AC electrical systems.

Calculate kW from Amps

Circuit Type

Current (Amps)

Voltage (Volts)

Power Factor (0-1)

Typical: Motors 0.85, Resistive loads 1.0

Results:

Kilowatts (kW)35.33

Watts (W)35,334

Horsepower (HP)47.36

Amps to kW Formulas

DC Circuit

kW = (A × V) ÷ 1000

Kilowatts = amps × volts ÷ 1000

AC Single Phase

kW = (A × V × PF) ÷ 1000

Include power factor for AC circuits

AC Three Phase

kW = (√3 × A × V × PF) ÷ 1000

√3 ≈ 1.732 for three-phase

Common Applications

•Motor sizing: Determine motor power requirements
•Load calculations: Calculate total facility load
•Energy costs: Estimate power consumption

What Is Amps to kW Conversion?

Converting amperes to kilowatts transforms a measure of electrical current into a measure of real power consumption. This conversion is essential for determining energy usage, sizing electrical equipment, and calculating operating costs. The formulas differ by circuit type: DC circuits use P(kW) = I × V ÷ 1000. Single-phase AC uses P(kW) = I × V × PF ÷ 1000. Three-phase AC uses P(kW) = I × V × PF × √3 ÷ 1000.

Power factor (PF) accounts for the phase difference between voltage and current in AC circuits, reducing real power below apparent power for inductive loads like motors. Understanding this conversion is fundamental to electrical engineering, energy management, and compliance with the National Electrical Code (NEC).

How to Calculate Amps to kW

1
Select Circuit Type
Choose DC, single-phase AC, or three-phase AC. Residential circuits are typically single-phase. Industrial and commercial facilities use three-phase for motors and heavy equipment.
2
Enter Current in Amps
Input the measured or rated current. Use a clamp ammeter for in-circuit measurements. For new installations, use equipment nameplate ratings or NEC Table 430.250 for motor full-load currents.
3
Enter Supply Voltage
Enter the circuit voltage: 120V or 240V for residential, 208V, 277V, or 480V for commercial. For three-phase, enter line-to-line voltage.
4
Set Power Factor (AC Only)
For AC circuits, enter the power factor. Resistive loads (heaters, incandescent lights) have PF ≈ 1.0. Motor loads typically range from 0.80-0.90. LED lighting runs 0.90-0.95.
5
Review kW Result
The calculated kW represents real power consumption. Multiply by hours of operation and electricity rate ($/kWh) to estimate operating costs.

Why Amps to kW Conversion Matters

Energy Cost Estimation

Electricity is billed in kWh. Converting equipment amps to kW, then multiplying by operating hours, gives energy consumption for accurate utility cost calculations and budgeting.

Circuit Breaker and Wire Sizing

NEC requires conductors and overcurrent protection based on amperage, while load calculations are often in kW. Converting between them ensures properly sized, code-compliant electrical installations.

Generator Sizing

When sizing backup generators, you need total kW demand from all connected loads. Converting each load from amps to kW and summing provides the minimum generator capacity required.

Electrical Panel Load Balancing

Balancing loads across panel phases requires knowing kW per circuit. Converting measured amps to kW for each circuit helps electricians distribute loads evenly and prevent phase imbalance.

DC Amps to kW Conversion Chart

Amps	kW @ 12V	kW @ 24V	kW @ 48V	kW @ 120V
10 A	0.12 kW	0.24 kW	0.48 kW	1.2 kW
20 A	0.24 kW	0.48 kW	0.96 kW	2.4 kW
50 A	0.6 kW	1.2 kW	2.4 kW	6 kW
100 A	1.2 kW	2.4 kW	4.8 kW	12 kW

Three Phase Amps to kW Chart (PF = 0.85)

Amps	kW @ 208V	kW @ 240V	kW @ 480V	kW @ 600V
10 A	2.97 kW	3.43 kW	6.86 kW	8.57 kW
20 A	5.94 kW	6.86 kW	13.71 kW	17.14 kW
50 A	14.85 kW	17.14 kW	34.28 kW	42.86 kW
100 A	29.70 kW	34.28 kW	68.57 kW	85.71 kW
200 A	59.39 kW	68.57 kW	137.14 kW	171.43 kW

Electrical Safety Tips & Best Practices

Power Factor Matters for AC

Ignoring power factor overestimates real power. A motor drawing 20A at 240V with PF=0.85 consumes 4.08 kW, not 4.8 kW. Always include power factor for accurate AC calculations.

Use Line-to-Line Voltage for Three-Phase

Three-phase calculations use line-to-line voltage (208V, 480V), not phase voltage. The √3 factor is already built into the formula to account for the voltage relationship.

Verify with a Power Meter

For the most accurate kW reading, use a true-power meter that measures voltage, current, and power factor simultaneously. This is more accurate than calculating from separate measurements.

Consider Demand Factor

Not all loads operate simultaneously at full capacity. Apply NEC demand factors (Article 220) when calculating total facility kW to avoid oversizing electrical services.

Frequently Asked Questions

How do I convert amps to kW?

Multiply amps by voltage and divide by 1000. For AC circuits, also multiply by the power factor. For three-phase, include the √3 (1.732) factor in the calculation.

What is the difference between kW and kVA?

kW is real power (actual work done), while kVA is apparent power (total power in the circuit). They differ due to power factor: kW = kVA × PF. For resistive loads, they are equal.

Why is three-phase power more efficient?

Three-phase power delivers constant power (no pulsation), uses less conductor material for the same power, and is more efficient for motors and large loads. It is standard for industrial and commercial applications.

How many kW is 30 amps at 240V?

For DC or resistive AC loads: 30A × 240V ÷ 1000 = 7.2 kW. For typical AC loads with 0.85 power factor: 6.12 kW. For three-phase at 240V with 0.85 PF: 10.6 kW.

What is the power factor and why does it matter?

Power factor is the ratio of real power (kW) to apparent power (kVA), ranging from 0 to 1. Low power factor means more current is needed for the same real power, increasing conductor losses, transformer loading, and potentially incurring utility penalty charges.

How do I convert kW back to amps?

Reverse the formula: For DC, Amps = kW × 1000 ÷ V. For single-phase AC, Amps = kW × 1000 ÷ (V × PF). For three-phase AC, Amps = kW × 1000 ÷ (V × PF × 1.732).

Is kW the same as kVA?

No. kW measures real power (useful work), while kVA measures apparent power (total power in the circuit). They are related by power factor: kW = kVA × PF. For purely resistive loads, kW equals kVA.

How many kW can a 200 amp service handle?

A 200A single-phase 240V service can theoretically supply 48 kW. However, NEC limits continuous loading to 80%, so practical capacity is about 38.4 kW. With demand factors applied to typical residential loads, a 200A service comfortably supports most homes.

Related Electrical Calculators

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

References & Industry Standards

NEC Article 220 - Branch-Circuit, Feeder, and Service Load Calculations
NEC Table 430.250 - Full-Load Current, Three-Phase AC Motors
IEEE 141 (Red Book) - Recommended Practice for Electric Power Distribution
ASHRAE 90.1 - Energy Standard for Buildings

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

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What Is Amps to kW Conversion?

How to Calculate Amps to kW

Select Circuit Type

Choose DC, single-phase AC, or three-phase AC. Residential circuits are typically single-phase. Industrial and commercial facilities use three-phase for motors and heavy equipment.

Enter Current in Amps

Input the measured or rated current. Use a clamp ammeter for in-circuit measurements. For new installations, use equipment nameplate ratings or NEC Table 430.250 for motor full-load currents.

Enter Supply Voltage

Enter the circuit voltage: 120V or 240V for residential, 208V, 277V, or 480V for commercial. For three-phase, enter line-to-line voltage.

Set Power Factor (AC Only)

For AC circuits, enter the power factor. Resistive loads (heaters, incandescent lights) have PF ≈ 1.0. Motor loads typically range from 0.80-0.90. LED lighting runs 0.90-0.95.

Review kW Result

The calculated kW represents real power consumption. Multiply by hours of operation and electricity rate ($/kWh) to estimate operating costs.

Why Amps to kW Conversion Matters

Energy Cost Estimation

Electricity is billed in kWh. Converting equipment amps to kW, then multiplying by operating hours, gives energy consumption for accurate utility cost calculations and budgeting.

Circuit Breaker and Wire Sizing

NEC requires conductors and overcurrent protection based on amperage, while load calculations are often in kW. Converting between them ensures properly sized, code-compliant electrical installations.

Generator Sizing

When sizing backup generators, you need total kW demand from all connected loads. Converting each load from amps to kW and summing provides the minimum generator capacity required.

Electrical Panel Load Balancing

Balancing loads across panel phases requires knowing kW per circuit. Converting measured amps to kW for each circuit helps electricians distribute loads evenly and prevent phase imbalance.

Amps

kW @ 12V

kW @ 24V

kW @ 48V

kW @ 120V

10 A

0.12 kW

0.24 kW

0.48 kW

1.2 kW

20 A

0.24 kW

0.48 kW

0.96 kW

2.4 kW

50 A

0.6 kW

1.2 kW

2.4 kW

6 kW

100 A

1.2 kW

2.4 kW

4.8 kW

12 kW

Amps

kW @ 208V

kW @ 240V

kW @ 480V

kW @ 600V

10 A

2.97 kW

3.43 kW

6.86 kW

8.57 kW

20 A

5.94 kW

6.86 kW

13.71 kW

17.14 kW

50 A

14.85 kW

17.14 kW

34.28 kW

42.86 kW

100 A

29.70 kW

34.28 kW

68.57 kW

85.71 kW

200 A

59.39 kW

68.57 kW

137.14 kW

171.43 kW

Electrical Safety Tips & Best Practices

Power Factor Matters for AC

Ignoring power factor overestimates real power. A motor drawing 20A at 240V with PF=0.85 consumes 4.08 kW, not 4.8 kW. Always include power factor for accurate AC calculations.

Use Line-to-Line Voltage for Three-Phase

Three-phase calculations use line-to-line voltage (208V, 480V), not phase voltage. The √3 factor is already built into the formula to account for the voltage relationship.

Verify with a Power Meter

For the most accurate kW reading, use a true-power meter that measures voltage, current, and power factor simultaneously. This is more accurate than calculating from separate measurements.

Consider Demand Factor

Not all loads operate simultaneously at full capacity. Apply NEC demand factors (Article 220) when calculating total facility kW to avoid oversizing electrical services.

Frequently Asked Questions

How do I convert amps to kW?

Multiply amps by voltage and divide by 1000. For AC circuits, also multiply by the power factor. For three-phase, include the √3 (1.732) factor in the calculation.

What is the difference between kW and kVA?

kW is real power (actual work done), while kVA is apparent power (total power in the circuit). They differ due to power factor: kW = kVA × PF. For resistive loads, they are equal.

Why is three-phase power more efficient?

How many kW is 30 amps at 240V?

For DC or resistive AC loads: 30A × 240V ÷ 1000 = 7.2 kW. For typical AC loads with 0.85 power factor: 6.12 kW. For three-phase at 240V with 0.85 PF: 10.6 kW.

What is the power factor and why does it matter?

How do I convert kW back to amps?

Reverse the formula: For DC, Amps = kW × 1000 ÷ V. For single-phase AC, Amps = kW × 1000 ÷ (V × PF). For three-phase AC, Amps = kW × 1000 ÷ (V × PF × 1.732).

Is kW the same as kVA?

No. kW measures real power (useful work), while kVA measures apparent power (total power in the circuit). They are related by power factor: kW = kVA × PF. For purely resistive loads, kW equals kVA.

How many kW can a 200 amp service handle?

References & Industry Standards

NEC Article 220 - Branch-Circuit, Feeder, and Service Load Calculations

NEC Table 430.250 - Full-Load Current, Three-Phase AC Motors

IEEE 141 (Red Book) - Recommended Practice for Electric Power Distribution

ASHRAE 90.1 - Energy Standard for Buildings

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