Power Converter

Convert between different power units instantly

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Popular Conversions
W to hp
kW to BTU/hr
hp to W
BTU/hr to kW
kcal/hr to W
VA to W
Ton to kW
PS to hp
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Unit Information

Watt (W): The SI unit of power, equal to one joule per second.

Kilowatt (kW): 1,000 watts.

Megawatt (MW): 1,000,000 watts.

Horsepower (hp): Approximately 745.7 watts.

Metric horsepower (PS): Approximately 735.5 watts.

BTU/hour: British Thermal Unit per hour, approximately 0.293 watts.

Ton of refrigeration: Approximately 3,516.85 watts.

Conversion Formula:

📚 Understanding Power Units: A Beginner's Guide

What This Converter Teaches You

This tool helps you understand how different power measurement systems connect. You'll learn:

  • How mechanical power (horsepower) relates to electrical power (watts)
  • Why cooling systems use "tons" instead of watts
  • How to compare engine power with heater power
  • The difference between real power (W) and apparent power (VA)
🔍 Understanding Your Input Value

When you enter a number like "100" in the converter:

  • 100 watts = A bright incandescent light bulb
  • 100 horsepower = A small car engine
  • 100 BTU/hour = Very small space heater
  • 100 VA = Computer or small appliance
🎯 When to Use Each Unit Type
Watts (W, kW, MW): Electrical devices, solar panels, light bulbs, electronics
Horsepower (hp, PS): Car engines, motors, pumps, lawnmowers
BTU/hour & Tons: Air conditioners, heaters, refrigerators
VA & kVA: Generators, transformers, industrial equipment
📖 Step-by-Step Conversion Explained

When you convert 100 watts to horsepower:

  1. The converter knows 1 hp = 745.7 W
  2. It divides: 100 W ÷ 745.7 W/hp = 0.1341 hp
  3. Think: "100 watts is about 13.4% of 1 horsepower"
⚠️ Common Student Mistakes
  • Mixing power and energy: Watts measure power (rate), kWh measures energy (total)
  • Forgetting time units: BTU/hr vs BTU - the "/hr" matters!
  • Metric vs Imperial hp: PS (German) ≠ hp (US/UK) - they're 1.4% different
  • Electrical confusion: VA is NOT always equal to Watts (depends on power factor)
💡 Unit Memorization Shortcuts

Easy Comparisons to Remember:

  • 1 horsepower ≈ ¾ of a kilowatt (actually 0.7457 kW)
  • 1 kW ≈ 3400 BTU/hr (actually 3412 BTU/hr)
  • 1 ton refrigeration ≈ 3.5 kW (cooling capacity)
  • 1000 VA ≈ 800-1000 W (depending on efficiency)
👁️ Visual Understanding Suggestions

To better understand power scales:

  • 1 watt: Smartphone charging (5W) ÷ 5
  • 100 watts: Old light bulb brightness
  • 1 horsepower: Can lift 550 lbs 1 foot in 1 second
  • 1 ton refrigeration: Melts 1 ton of ice in 24 hours
📝 Exam & Practical Usage Tips
  • Engineering exams: Remember 1 hp = 746 W (they round up)
  • HVAC work: 1 ton = 12,000 BTU/hr (industry standard)
  • Electrical exams: Power factor = Watts ÷ VA (always ≤ 1)
  • Quick estimates: 1 kW ≈ 1.34 hp ≈ 3412 BTU/hr
❓ General FAQ & Knowledge Base

Different industries developed their own units: mechanics used horsepower, electricity used watts, heating used BTU/hr. It's like different languages for the same concept.

Very accurate for most purposes. The converter uses standard international conversion factors. For critical engineering work, always verify with official standards.

No - energy (kWh, joules) measures total work done, while power (kW, hp) measures the rate. They're related by time: Energy = Power × Time.
Accuracy Disclaimer

This converter uses standardized conversion factors suitable for educational and general use. For precision engineering, scientific research, or commercial applications, always consult current official standards. Values may vary slightly between different standards (ISO, DIN, JIS, etc.).

Update Notice

Educational content updated November 2025. Conversion algorithms remain unchanged for consistency. Added beginner explanations and learning aids based on student feedback.

About Power Conversion

Power is the rate at which work is done or energy is transferred. It's a fundamental concept in physics and engineering, with applications ranging from electrical systems to mechanical engines and thermodynamics.

Common Use Cases
  • Electric motor ratings (watts or horsepower)
  • HVAC system sizing (BTU/hour or tons of refrigeration)
  • Energy consumption measurement (kilowatts)
  • Mechanical power transmission (horsepower)
  • Dietary energy burn rates (calories/second)
Frequently Asked Questions

kW (kilowatt) measures real power, while kVA (kilovolt-ampere) measures apparent power. For purely resistive loads, kW and kVA are equal, but for reactive loads (with inductance or capacitance), kVA will be higher due to power factor.

One mechanical horsepower (hp) is approximately 745.7 watts. It was originally defined as the power needed to lift 550 pounds one foot in one second. Metric horsepower (PS) is slightly less at about 735.5 watts.

A ton of refrigeration is a unit of power used in cooling systems. It's defined as the rate of heat transfer that results in the freezing or melting of 1 short ton (2,000 lb) of pure ice at 0°C in 24 hours, equivalent to approximately 3.51685 kW.

Unit Categories

SI Units
Watt (W) Kilowatt (kW) Megawatt (MW)
Imperial/Mechanical
Horsepower (hp) Metric horsepower (PS)
Electrical
Volt-ampere (VA) Kilovolt-ampere (kVA)
Thermal
BTU/hour Ton of refrigeration
Other Units
Calorie/second Foot-pound/min