A power converter translates measurements of power — the rate at which work is done or energy is transferred — from one unit to another. The SI unit is the Watt (W), defined as one Joule per second. Our converter supports 35+ power units used worldwide including every horsepower variant (mechanical, metric PS, boiler, electric, water, UK, French cheval-vapeur, German Pferdestärke), BTU-based units (BTU/h, BTU/min, BTU/s), calorie-based units, foot-pound units, refrigeration tons, poncelet, erg/second, and all SI prefixes from nanowatts to terawatts. Conversion happens via exact factors published by NIST and BIPM.
SI Power Units
Convert between Watts, kilowatts, megawatts, gigawatts and other International System (SI) power units with scientific precision.
Conversion Formula
1 kilowatt = 1000 watts
Common Conversions
Quick reference table| From | To | Result |
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How to Use This Power Converter
Engineered for engineers, scientists, and professionals working with power measurements. Follow these steps for accurate conversions.
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Select a Category Choose from 8 categories: SI units, Horsepower variants, BTU units, Calorie units, Foot-pound, Electrical, HVAC/Refrigeration, or Historical.
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Choose Source Unit Pick the unit you want to convert from (e.g., mechanical horsepower, kilowatts, BTU/h).
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Choose Target Unit Select the unit you want to convert to (e.g., metric PS, watts, tons of refrigeration).
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Enter Value Type the number — the result appears instantly with scientific precision as you type.
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Swap Units Click the swap button to instantly reverse the conversion direction.
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Verify with Formula The exact conversion factor is shown below for verification and documentation.
Horsepower Variants Around the World
Since James Watt coined the term "horsepower" in 1782 to market his steam engines, different countries and industries have defined their own variants. Our converter supports every one of them with precise conversion factors.
Mechanical HP (imperial)
745.699872 W
UK, USA, Canada
Metric HP (PS)
735.49875 W
Europe, Japan, Korea
Electric HP
746 W (exact)
International (motors)
Boiler HP
9,809.5 W
Steam & boiler industry
Water HP
746.043 W
US pump industry
Cheval-vapeur (CV)
735.49875 W
France, Italy, Spain
Pferdestärke (PS)
735.49875 W
Germany, Austria
DIN 66036 HP
735.49875 W
German automotive
Essential Power Formulas
Power is the rate of doing work. These fundamental formulas are used across mechanical, electrical, and thermal engineering disciplines worldwide.
P = W / t — Power = Work ÷ Time
P = F × v — Power = Force × Velocity
P = V × I — Power = Voltage × Current (DC)
P = I² × R — Power = Current² × Resistance
P = V² / R — Power = Voltage² ÷ Resistance
P = τ × ω — Power = Torque × Angular velocity
P = m × g × h / t — Lifting power
P = Q × ΔP — Hydraulic power (flow × pressure)
Why Engineers Choose ASLI FORM
Built for professionals working with power calculations across automotive, aerospace, HVAC, power generation, and academic disciplines.
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Scientific Precision Results accurate to 10 significant digits using NIST and BIPM standard conversion factors.
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Every HP Variant Mechanical, metric (PS), boiler, electric, water, UK, French cheval-vapeur, German Pferdestärke — all included.
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Instant Results Real-time conversion as you type — no submit button, no waiting, no delays.
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Works Offline All calculations run locally in your browser. Perfect for field work and remote sites.
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Universal Compatibility From keypad phones to 4K displays — responsive on every device worldwide.
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Zero Tracking No cookies, no analytics, no data collection. Your calculations are private.
Frequently Asked Questions
There are 7 major horsepower definitions used worldwide, each originating from different industries and countries:
- Mechanical HP (imperial): 745.699872 W — James Watt's 1782 original definition based on a horse lifting 33,000 lbs one foot in one minute. Used in UK, USA, Canada.
- Metric HP (PS / CV): 735.49875 W — Defined as the power to lift 75 kg one meter in one second. Used across Europe, Japan, Korea.
- Boiler HP: 9,809.5 W — Steam boiler industry standard, representing evaporation of 34.5 lbs of water per hour at 212°F.
- Electric HP: Exactly 746 W — Defined by international convention for electric motors.
- Water HP: 746.043 W — Used in US pump industry calculations.
- French cheval-vapeur (CV): 735.49875 W — Same as metric PS, used in France, Italy, Spain.
- German Pferdestärke (PS): 735.49875 W — DIN 66036 standard for German automotive.
Power is the RATE at which energy is used or produced, measured in Watts (Joules per second). Energy is the total AMOUNT of work done, measured in Joules, kWh, or BTU. Think of power as speed (km/h) and energy as distance (km). A 100W light bulb uses energy at a rate of 100 Joules per second; left on for 1 hour, it consumes 100 Watt-hours (0.1 kWh) of energy. The relationship is: Energy = Power × Time. This is why your electricity bill uses kWh (energy), not kW (power).
Use the exact conversion factors:
- Mechanical HP → kW: multiply by 0.745699872. Example: 100 hp = 74.57 kW
- Metric HP (PS) → kW: multiply by 0.73549875. Example: 100 PS = 73.55 kW
- Boiler HP → kW: multiply by 9.8095. Example: 10 boiler HP = 98.10 kW
- Electric HP → kW: multiply by 0.746. Example: 100 electric HP = 74.6 kW
A ton of refrigeration (TR) is a unit of power used primarily in HVAC and refrigeration engineering. It equals exactly 12,000 BTU/h or approximately 3.51685 kW. Historically, it represented the cooling power produced by melting one short ton (2000 lbs) of ice over 24 hours. Today, air conditioners, chillers, and refrigeration systems are still commonly rated in tons worldwide. A typical home central AC is 3-5 tons; large commercial systems may be hundreds of tons. Our converter lets you translate between TR, kW, BTU/h, and horsepower for HVAC calculations.
Yes. Our converter uses scientifically-verified conversion factors sourced from the National Institute of Standards and Technology (NIST), BIPM (International Bureau of Weights and Measures), and official standards bodies. Results are delivered to 10 significant digits of precision, suitable for:
- Mechanical engineering calculations
- Electrical engineering and power systems
- Automotive engine specifications
- HVAC system design
- Power plant operations
- Academic research and publications
The exact conversion factor is: 1 BTU/h = 0.29307107 W. This comes from the definition of the British Thermal Unit as the energy needed to raise 1 pound of water by 1°F. To convert in reverse: 1 W = 3.41214 BTU/h. This is commonly used for air conditioners, heaters, and appliances. For example, a 12,000 BTU/h air conditioner equals approximately 3.517 kW of cooling power. Our converter handles this and every other BTU variant (BTU/min, BTU/s) automatically.
The poncelet (p) is a historical unit of power from the metre-tonne-second system, defined as 100 kilogram-metres per second or exactly 980.665 W. Named after French engineer Jean-Victor Poncelet (1788–1867), it was used in 19th-century French engineering and is still referenced in historical technical literature. Our converter includes it for completeness and for working with legacy engineering documents.
Yes to both. Offline capability: Once the page loads, all calculations happen locally in your browser's JavaScript engine. No server calls, no API requests, no internet dependency. This makes it perfect for field work on power plants, automotive workshops, HVAC installations, and remote locations. Mobile compatibility: The interface uses a responsive design with a sticky sidebar on desktop, a grid layout on tablets, and an optimized drawer on mobile. Touch interactions, momentum scrolling, and responsive typography are all tuned for every screen size from 280px keypad phones to 4K displays.
Apparent power (measured in Volt-amperes, VA) and real power (measured in Watts) are related by the power factor (PF): Real Power (W) = Apparent Power (VA) × Power Factor. The power factor ranges from 0 to 1 and represents the efficiency of power usage. For purely resistive loads (heaters, incandescent bulbs), PF = 1 and W = VA. For motors and inductive loads, PF is typically 0.7-0.9. This converter focuses on real power and equivalent units; for apparent power calculations, use a dedicated VA-to-Watts calculator that includes the power factor parameter.
No. We do not collect, store, or transmit any values you enter. All calculations execute entirely in your browser's memory and are destroyed the moment you close the tab. There are no analytics scripts, no cookies for tracking, no third-party services that could observe your conversions. Your privacy is absolute. This is especially important for engineers working with proprietary designs, defense applications, or client-sensitive projects where data confidentiality is paramount.
These are all SI power units with metric prefixes indicating magnitude:
- Watt (W): Base unit. Power of a small LED bulb.
- Kilowatt (kW): 1,000 W. Household appliances, electric vehicles.
- Megawatt (MW): 1,000,000 W. Power plants, large ships, wind turbines.
- Gigawatt (GW): 1,000,000,000 W. National power grids, nuclear plants.
- Terawatt (TW): 1,000,000,000,000 W. Global energy consumption scale.
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