Horsepower to Watts Converter 2026 | HP to W Calculator

Horsepower to Watts Converter 2026

Convert HP to Watts (W) and Kilowatts (kW)

Accurate Power Unit Conversion Calculator

Horsepower (HP) and Watts (W) are both units of power measurement used across different industries and applications. Our horsepower to watts converter provides accurate conversions between mechanical horsepower, metric horsepower, electrical horsepower, and watts according to NIST standards and international unit definitions in 2026.

One mechanical horsepower equals exactly 745.699872 watts, while one metric horsepower (PS) equals 735.49875 watts. Understanding these conversions is essential for engineers, mechanics, and anyone working with motors, engines, or electrical systems. For more information on power measurements, visit Bureau International des Poids et Mesures.

⚡ Horsepower to Watts Calculator

Convert between different horsepower types and watts

Power Conversion

Horsepower Type

Horsepower Value

Output Unit

Horsepower to Watts Conversion Table 2026

This comprehensive conversion table shows common horsepower values converted to watts, kilowatts, and BTU/hour. The conversions use mechanical horsepower (hp) as defined by NIST standards where 1 hp = 745.699872 watts exactly.

Quick Conversion Reference

Horsepower (hp)	Watts (W)	Kilowatts (kW)	BTU/hour
0.25 hp	186.42 W	0.186 kW	636.15 BTU/h
0.5 hp	372.85 W	0.373 kW	1,272.30 BTU/h
1 hp	745.70 W	0.746 kW	2,544.60 BTU/h
2 hp	1,491.40 W	1.491 kW	5,089.19 BTU/h
5 hp	3,728.50 W	3.729 kW	12,722.98 BTU/h
10 hp	7,457.00 W	7.457 kW	25,445.97 BTU/h
25 hp	18,642.50 W	18.643 kW	63,614.91 BTU/h
50 hp	37,285.00 W	37.285 kW	127,229.83 BTU/h
75 hp	55,927.49 W	55.927 kW	190,844.74 BTU/h
100 hp	74,569.99 W	74.570 kW	254,459.66 BTU/h
150 hp	111,854.98 W	111.855 kW	381,689.48 BTU/h
200 hp	149,139.97 W	149.140 kW	508,919.31 BTU/h
500 hp	372,849.94 W	372.850 kW	1,272,298.28 BTU/h
1,000 hp	745,699.87 W	745.700 kW	2,544,596.57 BTU/h

1 Horsepower

Watts (W) 745.70 W

Kilowatts (kW) 0.746 kW

BTU/hour 2,544.60 BTU/h

5 Horsepower

Watts (W) 3,728.50 W

Kilowatts (kW) 3.729 kW

BTU/hour 12,722.98 BTU/h

10 Horsepower

Watts (W) 7,457.00 W

Kilowatts (kW) 7.457 kW

BTU/hour 25,445.97 BTU/h

100 Horsepower

Watts (W) 74,569.99 W

Kilowatts (kW) 74.570 kW

BTU/hour 254,459.66 BTU/h

Types of Horsepower Explained

Different horsepower definitions exist worldwide, each with specific conversion factors to watts. Our horsepower to watts calculator supports all major HP types used in automotive, industrial, and electrical applications.

Mechanical Horsepower (hp)

Conversion Factor: 1 hp = 745.699872 W

Region: United States, United Kingdom

Definition: 550 foot-pounds per second

Applications: American automotive engines, industrial motors, pumps

Standard: ASME, SAE, NIST

Metric Horsepower (PS/CV)

Conversion Factor: 1 PS = 735.49875 W

Region: Europe, Asia (except UK)

Definition: 75 kilogram-force meters per second

Applications: European vehicles, DIN ratings, metric machinery

Standard: DIN 66036, ISO standards

Electrical Horsepower

Conversion Factor: 1 hp = 746 W (exactly)

Region: International (electrical systems)

Definition: Defined as exactly 746 watts

Applications: Electric motors, generators, power systems

Standard: IEEE, IEC standards

Boiler Horsepower

Conversion Factor: 1 BHP = 9,810.657 W

Region: Industrial boiler applications

Definition: Evaporation of 34.5 lbs water/hour

Applications: Steam boilers, heating systems

Standard: ASME Boiler Code

Brake Horsepower (bhp)

Conversion Factor: 1 bhp = 745.699872 W

Region: Automotive industry worldwide

Definition: Power measured at engine output shaft

Applications: Engine dyno testing, automotive specifications

Standard: SAE J1349, DIN 70020

Indicated Horsepower (ihp)

Conversion Factor: 1 ihp = 745.699872 W

Region: Marine and industrial engines

Definition: Theoretical power from cylinder pressure

Applications: Engine design, thermodynamic calculations

Standard: Engineering calculations

Conversion Formulas and Calculations

Converting between horsepower and watts requires understanding the exact conversion factors. Our horsepower to watts converter uses these precise formulas for accurate results in engineering and technical applications.

📐 Primary Conversion Formulas:

Mechanical HP to Watts: W = hp × 745.699872
Metric HP to Watts: W = PS × 735.49875
Electrical HP to Watts: W = hp × 746 (exact)
Boiler HP to Watts: W = BHP × 9,810.657
Watts to HP: hp = W ÷ 745.699872
Kilowatts to HP: hp = kW × 1.34102

Example Calculations

Example 1: Engine Power

Given: 150 hp engine

Calculate: Power in kilowatts

Solution: 150 hp × 745.699872 W/hp = 111,854.98 W = 111.855 kW

Result: 150 horsepower = 111.855 kilowatts

Example 2: Electric Motor

Given: 7.5 kW motor

Calculate: Equivalent horsepower

Solution: 7.5 kW × 1.34102 hp/kW = 10.058 hp

Result: 7.5 kilowatts ≈ 10 horsepower

Example 3: European Vehicle

Given: 200 PS (metric HP)

Calculate: Power in watts and mechanical HP

Solution: 200 PS × 735.49875 W/PS = 147,099.75 W = 197.3 hp

Result: 200 metric HP = 197.3 mechanical HP

Example 4: Industrial Pump

Given: 50,000 watts

Calculate: Required motor horsepower

Solution: 50,000 W ÷ 745.699872 W/hp = 67.05 hp

Result: Select 75 hp motor (next standard size)

Common Applications and Use Cases

Horsepower to watts conversions are essential across numerous industries. Understanding when to use each unit helps engineers, technicians, and consumers make informed decisions about power requirements.

Automotive Engines

Typical Range: 100-500 hp (75-375 kW)

Usage: Car and truck engine power ratings

Note: US uses hp, Europe uses PS/kW

Example: 200 hp sports car = 149.14 kW

Electric Motors

Typical Range: 0.5-200 hp (0.37-150 kW)

Usage: Industrial machinery, pumps, compressors

Note: Usually specified in kW internationally

Example: 10 hp motor = 7.457 kW

HVAC Systems

Typical Range: 1-50 hp (0.75-37 kW)

Usage: Air handlers, chillers, cooling towers

Note: Energy efficiency calculations require watts

Example: 5 hp fan = 3.729 kW power draw

Marine Engines

Typical Range: 50-5,000 hp (37-3,730 kW)

Usage: Boat and ship propulsion

Note: Shaft horsepower (shp) commonly used

Example: 300 hp outboard = 223.71 kW

Power Tools

Typical Range: 0.5-5 hp (0.37-3.7 kW)

Usage: Table saws, routers, compressors

Note: Peak hp often marketing inflated

Example: 2 hp router = 1.491 kW motor

Agricultural Equipment

Typical Range: 20-600 hp (15-450 kW)

Usage: Tractors, combines, irrigation pumps

Note: PTO (power take-off) hp specified

Example: 100 hp tractor = 74.57 kW PTO

Watts vs. Horsepower: When to Use Each

While both measure power, watts and horsepower serve different purposes depending on context, region, and industry standards. Understanding when to use each unit ensures clear communication and compliance with specifications.

✅ Use Watts/Kilowatts When:

Electrical systems: All electrical power measurements use watts (SI unit)
International specifications: Most countries outside North America use kW
Energy calculations: Electrical energy consumption measured in watt-hours (Wh) or kilowatt-hours (kWh)
Scientific/engineering: SI unit system requires watts for technical documentation
Solar panels: Solar power always specified in watts (W) or kilowatts (kW)
LED/lighting: Modern lighting power measured in watts

⚠️ Use Horsepower When:

Automotive industry: Traditional engine power ratings in North America
Marketing/consumer products: General public familiar with HP for engines and motors
Historical data: Comparing with older equipment specifications
Specific industries: Marine, agriculture, and certain machinery sectors prefer HP
US regulations: Some US standards still reference horsepower
Colloquial usage: Common expression like "horsepower rating" understood by consumers

Historical Origin of Horsepower

The horsepower unit was developed by Scottish engineer James Watt in the late 18th century to market his steam engines by comparing their power output to draft horses, which were the primary power source of that era.

James Watt's Definition (1782)

Original Standard: One horse could lift 330 pounds of coal 100 feet in one minute

Calculation: 330 lbs × 100 ft / 1 min = 33,000 ft-lbf/min

Power Output: Equivalent to 550 ft-lbf/sec or 745.7 watts

Purpose: Marketing tool to sell steam engines

Modern Standardization

1959 Agreement: International yard and pound definitions standardized

Exact Definition: 1 hp = 745.699872 watts (mechanical)

Metric Equivalent: 1 PS = 735.49875 watts (metric HP)

Current Use: Declining in favor of SI units (watts)

Actual Horse Power

Average Horse: Can produce 15 hp for short bursts

Sustained Output: Approximately 1 hp over working day

Watt's Estimate: Intentionally conservative for marketability

Interesting Fact: A fit human can produce 1.2 hp briefly, 0.1 hp sustained

Energy Consumption and Cost Calculations

Converting horsepower to watts enables accurate energy consumption and electricity cost calculations. This is essential for industrial operations, facility management, and equipment selection to optimize operational costs.

Energy and Cost Formula

Motor Size	Power (kW)	Energy/Hour (kWh)	Cost/Hour @ £0.15/kWh	Cost/Day (24h)
1 hp	0.746 kW	0.746 kWh	£0.11	£2.69
5 hp	3.729 kW	3.729 kWh	£0.56	£13.44
10 hp	7.457 kW	7.457 kWh	£1.12	£26.85
25 hp	18.643 kW	18.643 kWh	£2.80	£67.11
50 hp	37.285 kW	37.285 kWh	£5.59	£134.23
100 hp	74.570 kW	74.570 kWh	£11.19	£268.45
200 hp	149.140 kW	149.140 kWh	£22.37	£536.90
500 hp	372.850 kW	372.850 kWh	£55.93	£1,342.26

5 HP Motor Operating Cost

Power 3.729 kW

Cost/Hour £0.56

Cost/Day £13.44

25 HP Motor Operating Cost

Power 18.643 kW

Cost/Hour £2.80

Cost/Day £67.11

100 HP Motor Operating Cost

Power 74.570 kW

Cost/Hour £11.19

Cost/Day £268.45

Horsepower to Watts FAQs

How many watts is 1 horsepower?

One mechanical horsepower equals exactly 745.699872 watts. For practical purposes, 1 hp ≈ 746 watts or 0.746 kilowatts. Metric horsepower (PS) is slightly less at 735.49875 watts. Electrical horsepower is defined as exactly 746 watts.

Is horsepower greater than watts?

Yes, one horsepower equals approximately 746 watts, making horsepower a larger unit. To convert HP to watts, multiply by 745.7. Conversely, to convert watts to HP, divide by 745.7. For example, 10 hp = 7,457 watts, while 1,000 watts = 1.34 hp.

What's the difference between mechanical and metric horsepower?

Mechanical horsepower (hp) equals 745.7 watts and is used primarily in North America. Metric horsepower (PS, CV, or ch) equals 735.5 watts and is used in Europe and Asia. The difference is about 1.4%—a 100 hp engine equals approximately 98.6 PS, while 100 PS equals 101.4 hp.

How do I calculate electricity cost from horsepower?

First convert HP to kilowatts (multiply by 0.746), then multiply by operating hours and your electricity rate. Formula: Cost = HP × 0.746 × hours × rate per kWh. Example: 10 hp motor running 8 hours at £0.15/kWh = 10 × 0.746 × 8 × 0.15 = £8.95.

Why do we still use horsepower instead of watts?

Horsepower persists primarily in North American automotive and industrial applications due to historical familiarity and marketing tradition. Most of the world has transitioned to kilowatts (kW) as the standard power unit. The automotive industry continues using HP because consumers understand it, though technical specifications increasingly include both HP and kW.

How many horsepower is a kilowatt?

One kilowatt equals approximately 1.34102 horsepower. To convert kW to HP, multiply by 1.341. To convert HP to kW, multiply by 0.746. For example, a 100 kW motor = 134.1 hp, while a 100 hp motor = 74.6 kW.

What is brake horsepower (bhp) vs. horsepower?

Brake horsepower (bhp) measures actual power at an engine's output shaft (measured on a dynamometer or "brake"). Standard horsepower can refer to indicated power (theoretical from cylinder pressure) or rated power. BHP is always lower than indicated HP due to frictional losses. The conversion to watts is the same: 1 bhp = 745.7 watts.

Can a human produce one horsepower?

A fit human can briefly produce about 1.2 horsepower (895 watts) for a few seconds during maximum exertion. However, sustained output over hours is only about 0.1 horsepower (75 watts). Elite cyclists can sustain 0.4-0.5 hp (300-400 watts) for extended periods. This demonstrates why James Watt's original comparison was reasonable—horses can sustain roughly 1 hp over a working day.

Do electric motors use horsepower or kilowatts?

Electric motors are increasingly rated in kilowatts (kW) globally, though North American markets often use horsepower. Technically, 1 electrical horsepower is defined as exactly 746 watts. Motor nameplates typically show both ratings—for example, "5 hp / 3.7 kW." Industrial specifications worldwide prefer kW for consistency with electrical power calculations.

How accurate is the horsepower to watts conversion?

The conversion is exact by definition: 1 mechanical hp = 745.699872 watts precisely. This is based on standardized international agreements. However, when manufacturers rate equipment, actual power output can vary ±5-10% depending on testing conditions, temperature, efficiency, and measurement methods (SAE vs. DIN standards). Always check which HP standard is being referenced.