Skip to main content
Unit Converter
engineering Group•7 Units• Free Online Precision Tool

Power Converter

Convert power ratings between Watts, Kilowatts, Mechanical Horsepower, Metric PS, and BTU per hour with real-time bidirectional calculations and engineering formulas.

Explore Power Guide & Formulas↓View Power Converter Chart→
Formula

Simultaneous Category Equivalents

Click any unit card to set it as the active primary input

Zero-latency client-side engine
Copied to clipboard

Popular Power Conversion Shortcuts

Instant pair conversions with verified scientific and mathematical formulas

Quick Pairs
HP to Watts→
1 hp = 745.70 W
KW to HP→
1 kW = 1.3410 hp
HP to KW→
100 hp = 74.57 kW
Watts to HP→
1,000 W = 1.3410 hp
KW to BTU/hr→
1 kW = 3,412.14 BTU/h
BTU/hr to KW→
12,000 BTU/h = 3.517 kW
Metric PS to HP→
100 PS = 98.63 hp
MW to KW→
1 MW = 1,000 kW

Power Reference Equivalents (1 Watt)

Standard ratios measured against the base Watt (W)

Reference Table
Unit NameSymbolEquivalent in 1 WQuick Pair Page
WattW1 W = 1 WBase Unit
KilowattkW1 W = 0.001 kWW to kW →
MegawattMW1 W = 1.000000e-6 MWW to MW →
Horsepower (Metric, PS)hp (M)1 W = 0.00136 hp (M)W to hp (M) →
Horsepower (Mechanical, Imperial)hp1 W = 0.001341 hpW to hp →
BTU per hourBTU/h1 W = 3.412142 BTU/hW to BTU/h →
Foot-pound per minuteft·lbf/min1 W = 44.253729 ft·lbf/minW to ft·lbf/min →

Power Output Conversion Lookup Chart

Quick lookup reference table for Watts, Kilowatts (kW), Mechanical Horsepower (hp), and Metric PS

Lookup Matrix
Power BenchmarkWatts (W)Kilowatts (kW)Horsepower (hp)Metric PS (hp M)
Smartphone Fast Charger20 W0.02 kW0.027 hp0.027 PS
Human Brain Metabolism20 W0.02 kW0.027 hp0.027 PS
Resting Human Body Heat100 W0.10 kW0.134 hp0.136 PS
Pro Cyclist Sustained Sprint400 W0.40 kW0.536 hp0.544 PS
One Mechanical Horsepower (1 hp)746 W0.75 kW1.000 hp1.014 PS
One Metric Horsepower (1 PS)735 W0.74 kW0.986 hp1.000 PS
Residential Microwave Oven1,200 W1.20 kW1.609 hp1.632 PS
Electric Kettle / Space Heater2,000 W2.00 kW2.682 hp2.719 PS
Small Lawn Mower Engine (5 hp)3,728 W3.73 kW5.000 hp5.069 PS
Standard Home Central AC (3 Ton)10,551 W10.55 kW14.150 hp14.345 PS
Economy Subcompact Car (100 hp)74,570 W74.57 kW100.000 hp101.387 PS
Midsize Sedan Gasoline Engine150,000 W150.00 kW201.153 hp203.943 PS
Tesla Model 3 Dual Motor (350 kW)350,000 W350.00 kW469.358 hp475.867 PS
Formula 1 Hybrid Power Unit746,000 W746.00 kW1,000.000 hp1,013.870 PS
Commercial Wind Turbine (3 MW)3,000,000 W3,000.00 kW4,023.070 hp4,078.868 PS
MECHANICAL & ELECTRICAL ENGINEERING GUIDE

Complete Guide to the Online Power Converter Calculator

Master power rating conversions across Watts, Kilowatts, Megawatts, Mechanical Horsepower, Metric PS, and BTU per hour with our high-precision Power Converter, formulas, and automotive motor tables.

The Next Generation of Online Power Converter Tools

Power quantifies the rate at which energy is generated, transferred, or consumed over time. Accurate power unit conversion is vital across automotive vehicle engineering (combustion engines and EV battery motors), commercial electrical utility distribution, HVAC heating and cooling sizing, solar inverter design, and industrial manufacturing. Whether translating electric motor ratings from kilowatts to horsepower, comparing European sports car specs in metric PS, or calculating furnace heating capacities in BTU per hour, an accurate Power Converter is essential.

Conventional online calculators force users through repetitive single-pair dropdowns. Our modern power converter calculator delivers an instantaneous multi-unit evaluation matrix. Entering any power measurement into any active unit field evaluates every corresponding SI metric, electrical, automotive, and HVAC scale simultaneously in real time.

Horsepower to Watts & kW: Exact Mathematical Formulations

Bridging imperial mechanical horsepower and metric kilowatts requires strict statutory conversion factors established by international metrology standards:

Horsepower to Kilowatts Formula

Multiply horsepower by 0.74569987:

kW = Horsepower × 0.74569987

Example: 250 hp × 0.7457 = 186.42 kW

Kilowatts to Horsepower Formula

Multiply kilowatts by 1.341022:

Horsepower = kW × 1.341022

Example: 100 kW × 1.34102 = 134.10 hp

BTU/hr to Kilowatts Formula

Divide BTU/h by 3,412.142:

kW = BTU/h ÷ 3,412.142

Example: 36,000 BTU/h ÷ 3,412.142 = 10.55 kW

Metric PS to Mechanical HP

Multiply metric PS by 0.98632:

HP = Metric PS × 0.98632

Example: 400 PS × 0.98632 = 394.53 hp

Complete Units of Power Directory

Our Power Converter supports every significant scale across electrical engineering, propulsion, and thermodynamics:

  • Watt (W): The SI base derived unit of power (1 Joule per second). The global standard for electronics, consumer appliances, and LED illumination.
  • Kilowatt (kW): Exactly 1,000 Watts (approx. 1.341 hp). Standard for electric vehicle motor output ratings, solar panel arrays, and industrial machinery.
  • Megawatt (MW): Exactly 1,000,000 Watts (1,000 kW). Standard for utility-scale electrical power plants, wind turbines, and naval propulsion.
  • Horsepower (hp mechanical): Exactly 745.69987 Watts (550 ft·lbf/s). Standard automotive engine output specification in North America.
  • Metric Horsepower (PS / ch): Exactly 735.49875 Watts (75 kgf·m/s). Standard automotive engine rating in Germany, France, Japan, and continental Europe.
  • BTU per Hour (BTU/h): Exactly 0.29307107 Watts. Standard thermal capacity rating for residential air conditioners, furnaces, and heat exchangers.
  • Foot-pound per Minute (ft·lbf/min): Exactly 0.02259697 Watts. Historic mechanical power rating (33,000 ft·lbf/min = 1 mechanical horsepower).

Practical Engineering Scenarios: Electric Vehicles, HVAC & Engines

Power conversions directly inform vehicle purchasing, electrical service sizing, and climate control engineering:

Electric Vehicle (EV) Motor Ratings vs. Gas Engines

Automakers market electric vehicle motor output in kilowatts (kW) in international jurisdictions and in horsepower (hp) in North America. An EV rated at 300 kW delivers 300 × 1.341 = 402.3 hp, providing consumers with an immediate apples-to-apples comparison against traditional internal combustion engines.

HVAC Air Conditioning Sizing & Tonnage

Residential air conditioners are categorized by "Tons of refrigeration" (1 Ton = 12,000 BTU/h = 3.517 kW). Sizing a replacement heat pump requires converting home heating load calculations in kilowatts back to equipment nominal BTU/hr ratings.

Backup Emergency Generator Sizing

Electric backup generators are rated by electrical kilowatt output (e.g., 20 kW standby generator), while their internal combustion engines are rated in horsepower. Converting between engine hp and generator kW ensures proper mechanical matching under peak inductive motor starting loads.

Why toolunitconverter.com is the Best Online Power Converter

Our Power Converter delivers high-performance speed, auditability, and mobile ease:

Instant Client-Side Evaluation

All 7 power units compute instantaneously in your local browser without network roundtrips or server latency.

Multi-Unit Synchronous Matrix

Type any power figure in Watts, kW, hp, or BTU/h, and every other scale recalibrates synchronously.

One-Click Clipboard Copying

Copy exact formatted values or raw numbers straight into engineering CAD packages, spec sheets, or spreadsheets.

Auditable Mathematical Formulas

Grounded in official NIST and BIPM definitions for bit-perfect accuracy across all power scales.

About Power Units & Formulas

Multiply the power by the factor relative to 1 Watt (W).

WattW

SI unit of power (1 J/s)

KilowattkW

1,000 Watts

MegawattMW

1,000,000 Watts

Horsepower (Metric, PS)hp (M)

German PS / European metric horsepower (75 kgf·m/s)

Horsepower (Mechanical, Imperial)hp

550 ft·lbf/s or ~745.7 Watts

BTU per hourBTU/h

HVAC cooling/heating power capacity

Foot-pound per minuteft·lbf/min

Mechanical power unit

FREQUENTLY ASKED QUESTIONS

Power Converter FAQs

Frequently asked questions regarding power conversion metrics, formulas, and real-world calculation standards

How many Watts are in 1 Horsepower?

The exact wattage of 1 horsepower depends on which legal engineering standard is applied:

  • Mechanical / Imperial Horsepower (hp): Exactly 745.69987158227 Watts (typically rounded to 745.7 W). Defined by James Watt as 550 foot-pounds of work per second.
  • Metric Horsepower (PS, ch, or cv): Exactly 735.49875 Watts (approx. 735.5 W). Defined in continental Europe as the power required to raise a 75 kg mass against Earth gravity by 1 meter in 1 second.
  • Electrical Horsepower (US): Standardized in the United States by the National Electrical Code as exactly 746 Watts.
  • Boiler Horsepower: Approximately 9,809.5 Watts (used for industrial steam boilers).

How do I convert kW to Horsepower?

To convert Kilowatts (kW) to Mechanical Horsepower (hp), multiply the kW figure by 1.341022 or divide by 0.74569987: hp = kW × 1.341022.

Step-by-Step Practical Examples:

  • Electric Vehicle Sizing: An electric motor rated at 150 kW produces: 150 × 1.34102 = 201.15 hp.
  • Metric Horsepower (kW to PS): Multiply kW by 1.35962: 150 kW × 1.35962 = 203.94 PS.
  • Reverse Conversion (HP to kW): Multiply horsepower by 0.7457 (e.g., 300 hp × 0.7457 = 223.71 kW).

What is the formula to calculate power?

The fundamental physical definition of power is the rate at which energy is transferred or work is performed per unit of time: Power = Work ÷ Time (P = W ÷ Δt).

  • SI Derived Definition: 1 Watt (W) equals 1 Joule of energy expended per second (1 W = 1 J/s).
  • Electrical DC Power Equation: Power (Watts) = Voltage (Volts) × Current (Amperes) (P = V × I).
  • Rotational Mechanical Power: In rotating engines and turbines: Power (Watts) = Torque (N·m) × Angular Velocity (rad/s). In imperial units: Horsepower = (Torqueft·lb × RPM) ÷ 5,252.

What is 1 Watt in physical terms?

In physics, 1 Watt (W) is the International System of Units (SI) unit of power. It represents the expenditure of 1 Joule of energy every second (1 W = 1 J/s = 1 N·m/s = 1 kg·m²/s³).

To contextualize 1 Watt in real-world scenarios:

  • The electrical consumption of a modern energy-efficient LED nightlight.
  • The mechanical work performed when lifting a 100-gram mass vertically at a steady velocity of 1 meter per second.
  • Approximately 1/100 of the resting thermal heat dissipated continuously by an adult human body (~100 W).

How do I convert BTU/hr to Kilowatts (kW)?

To convert British Thermal Units per hour (BTU/h) to Kilowatts (kW), divide the BTU/h figure by 3,412.142 or multiply by 0.000293071: kW = BTU/h ÷ 3,412.142.

HVAC Equipment Capacity Example:

  • A residential heat pump rated at 24,000 BTU/h (2 Tons of refrigeration) delivers: 24,000 ÷ 3,412.142 = 7.034 kW of thermal heating or cooling power.
  • A large commercial boiler rated at 100,000 BTU/h equals: 100,000 × 0.00029307 = 29.31 kW.
  • Reverse Conversion (kW to BTU/h): Multiply kW by 3,412.142 (e.g., 5 kW × 3,412.142 = 17,060.7 BTU/h).

What is the difference between mechanical hp and metric hp (PS)?

The distinction between mechanical horsepower and metric horsepower (PS / ch) is rooted in historical metrology:

  • Mechanical Horsepower (hp / imperial): Formulated in Britain by James Watt, defined as lifting 550 pounds by 1 foot in 1 second (550 ft·lbf/s), equivalent to exactly 745.69987 Watts.
  • Metric Horsepower (PS / Pferdestärke / ch): Formulated in continental Europe under the metric system, defined as raising a 75 kilogram mass against standard gravity (9.80665 m/s²) by 1 meter in 1 second (75 kgf·m/s), equivalent to exactly 735.49875 Watts.
  • Magnitude Difference: Mechanical horsepower is approximately 1.39% more powerful than metric horsepower: 1 hp = 1.01387 PS (and 1 PS = 0.98632 hp). European automakers frequently market higher PS numbers that must be converted when reviewing US horsepower specifications.