Power Conversion Calculator

Enter any positive number for instant conversion
Kilowatts (kW)
0.000
BTU per Hour (BTU/hr)
0.000
Mechanical Horsepower (hp)
0.000000
Metric Horsepower (PS)
0.000000
Electric Horsepower (hp)
0.000000
Calories per Second (cal/s)
0.000
Erg per Second (erg/s)
0
Foot-pound per Minute (ft⋅lbf/min)
0.000
Tons of Refrigeration
0.000000
Air Horsepower (ahp)
0.000000
Boiler Horsepower (hp(S))
0.000000
Kilocalories per Hour (kcal/h)
0.000

Understanding Power Conversion

Power is the rate at which energy is transferred or converted, and understanding how to convert between different power units is essential for engineers, scientists, and anyone working with energy systems. This comprehensive guide will help you master power conversions and understand the practical applications of each unit.

How to Use This Power Converter

  1. Enter your power value in watts in the input field above
  2. View instant results - all conversions appear automatically in real-time
  3. Copy the values you need for your calculations or reference
  4. Use the reset function to clear inputs and start fresh
Pro Tip: This calculator works in real-time, so you can experiment with different values to understand the relationships between units. All results are calculated to high precision for scientific and engineering applications.

Calculation Methodology & Scientific Basis

Our power converter uses internationally recognized conversion factors established by the National Institute of Standards and Technology (NIST) and the International System of Units (SI). Each conversion is based on the fundamental definition of the watt as one joule per second.

1 Watt = 1 Joule/Second = 1 kg⋅m²/s³
Base SI unit definition from the International Bureau of Weights and Measures (BIPM)

Key Conversion Factors

Unit Conversion Factor Common Use
Kilowatt (kW) 1 W = 0.001 kW Electrical power rating
BTU/hr 1 W = 3.41214 BTU/hr HVAC and cooling systems
Mechanical HP 1 W = 0.00134102 hp Automotive and machinery
Metric HP (PS) 1 W = 0.00135962 hp European automotive
Electric HP 1 W = 0.00134048 hp Electric motors
Calories/second 1 W = 0.238846 cal/s Metabolic calculations
Erg/second 1 W = 10,000,000 erg/s Physics calculations
ft⋅lbf/min 1 W = 44.2537 ft⋅lbf/min Mechanical engineering
Tons of Refrigeration 1 W = 0.000284345 tons Air conditioning capacity

Understanding Your Results

Each power unit serves specific industries and applications. Here's what your conversion results mean in practical terms:

Kilowatts (kW) are the standard unit for electrical power consumption. Your monthly electricity bill is calculated in kilowatt-hours (kWh), which is kilowatts multiplied by time. A typical household uses 1-2 kW during normal operation.

BTU per hour (BTU/hr) measures heating and cooling capacity. Air conditioners are often rated in BTU/hr - a 12,000 BTU/hr unit (1 ton) can cool approximately 400-500 square feet. This conversion is crucial for HVAC sizing calculations.

Horsepower comes in three variants: mechanical (traditional US standard), metric (European standard), and electric (for motors). The differences are small but important for precision applications. A typical car engine produces 100-300 horsepower.

Calories per second relates to metabolic energy transfer. The human body at rest consumes about 80-100 watts, equivalent to roughly 19-24 calories per second. This unit helps understand energy expenditure in biological systems.

Precision Note: Our calculator rounds results to appropriate decimal places based on typical precision requirements for each unit. For critical engineering applications, always verify calculations independently and consider significant figures.

Real-World Applications and Examples

HVAC System Sizing

When sizing air conditioning systems, engineers convert electrical power consumption to cooling capacity. A 3.5 kW (3,500 watt) air conditioning unit produces approximately 11,942 BTU/hr of cooling capacity. This helps determine if the system can adequately cool a given space.

Automotive Performance

Modern electric vehicles often specify power in both kilowatts and horsepower. A Tesla Model S motor rated at 285 kW produces approximately 382 mechanical horsepower. Understanding both units helps compare electric and conventional vehicles.

Industrial Motor Selection

Industrial motors are often specified in different power units depending on the region. A 37 kW industrial motor equals approximately 49.6 mechanical horsepower or 50.3 metric horsepower. This conversion is essential when sourcing equipment internationally.

Energy Efficiency Analysis

In metabolic studies, researchers convert mechanical work to calories. A person cycling at 200 watts for one hour expends approximately 172 calories (200 W × 3600 s × 0.238846 cal/s ÷ 1000).

Common Power Conversion Mistakes to Avoid

Many people confuse power with energy. Power is the rate of energy transfer (watts), while energy is the total amount transferred over time (watt-hours or joules). A 100-watt light bulb uses 100 watts of power, but consumes 1 kilowatt-hour of energy if left on for 10 hours.

Another common mistake is using the wrong type of horsepower for calculations. Always verify whether you need mechanical, metric, or electric horsepower for your specific application. The differences may seem small, but they matter in precision engineering.

When working with BTU/hr conversions, remember that this measures power (rate), not total energy. Don't confuse BTU/hr with BTU - the latter is a unit of energy, not power.

Advanced Power Conversion Concepts

Efficiency Considerations

Real-world power conversions involve efficiency losses. When an electric motor converts electrical power to mechanical power, efficiency is typically 85-95%. A 10 kW electric motor might only deliver 9 kW of mechanical power due to heat losses and friction.

Peak vs. Continuous Power

Many devices have different peak and continuous power ratings. Electric motors can often handle 150-200% of their rated power for short periods but will overheat if operated continuously at these levels. Always consider the duty cycle when performing power calculations.

Power Factor in AC Systems

In alternating current (AC) electrical systems, power factor affects the relationship between apparent power (VA) and real power (watts). A power factor less than 1.0 means you're drawing more current than necessary, affecting efficiency and utility costs.

Industry-Specific Power Units

Refrigeration Industry

The refrigeration industry uses tons of refrigeration, where one ton equals the cooling power of one ton of ice melting over 24 hours. This equals 3,516.85 watts or 12,000 BTU/hr. Understanding this conversion helps size commercial refrigeration systems.

Physics and Scientific Research

In physics, power is often expressed in ergs per second for atomic and molecular calculations. One watt equals 10,000,000 erg/s. This unit helps understand energy transfer at microscopic scales.

Exercise and Sports Science

Exercise physiologists measure human power output in watts. Elite cyclists can sustain 300-400 watts for extended periods, while sprint efforts may exceed 1,000 watts. These measurements help optimize training and performance.

Future of Power Measurement

As renewable energy grows, power conversion becomes increasingly important. Solar panels are rated in watts peak (Wp), wind turbines in kilowatts, and energy storage in kilowatt-hours. Understanding these conversions helps evaluate renewable energy systems effectively.

Smart grids and Internet of Things (IoT) devices require precise power measurements for optimization. Real-time power conversion between different units enables better energy management and cost savings.

Important Note: Always double-check your conversions and understand the context of each measurement. When in doubt, consult multiple sources and verify calculations independently.