Horsepower to Watts Converter | Free Online hp to W Calculator

⚡ Free Online Power Converter

Horsepower to Watts Converter

Instantly Convert HP ↔ Watts — Mechanical, Electrical & Metric

Convert horsepower to watts (hp → W) or watts to horsepower (W → hp) instantly. Supports all three HP types — mechanical, electrical, and metric — with exact formulas, full reference tables, and real-world examples. Free, no sign-up needed.

✅ HP → Watts

✅ Watts → HP

✅ All 3 HP Types

✅ kW & kW Output

Horsepower to Watts (hp to W) Converter

Horsepower and watts are both units of power — the rate at which energy is used or produced. Our HP to watts converter supports all three horsepower types using their exact, internationally defined watt equivalents.

🐎 What is Horsepower?

Horsepower (hp) is a unit of power originally defined by James Watt in the late 18th century to compare the output of steam engines to the power of draft horses. Today, three main types exist: mechanical (imperial) hp, electrical hp, and metric hp — each with a slightly different watt equivalent. It is widely used to rate engines, motors, turbines, and other power sources.

⚡ What is a Watt?

The watt (W) is the SI unit of power, defined as one joule per second (J/s). It is named after Scottish inventor James Watt. One watt equals the power produced when a current of one ampere flows through a resistance of one ohm. Watts are used universally to measure electrical power, engine output in metric countries, and energy consumption for appliances, solar panels, and industrial machinery.

🔢 Three HP Conversion Factors

There are three conversion factors depending on the HP type: Mechanical hp = 745.699872 W (used for engines and motors in the US); Electrical hp = 746 W (exact, used for electric motors); Metric hp = 735.49875 W (used in Europe and automotive specs). The mechanical hp is the most common in general usage. When in doubt, use 1 hp ≈ 745.7 W.

⚡ Horsepower ↔ Watts Converter

Select your HP type, choose direction, enter a value, and convert instantly

Step 1 — Select Horsepower Type:

Value in Horsepower (hp)

Result in Watts (W)

Converted Value

— W

—

Kilowatts (kW)

—

Megawatts (MW)

—

BTU/hour

—

Joules/sec (J/s)

—

Three Types of Horsepower Explained

Not all horsepower is equal — three different definitions exist, each yielding a slightly different watt value. Knowing which type is being used is critical for accurate conversion, particularly in automotive, electrical, and engineering contexts.

HP Type	Symbol	Watts (W)	Used For	Regions
Mechanical (Imperial) HP	hp(I) or hp	745.699872 W	Engines, pumps, motors, general US usage	USA, UK, Canada
Electrical HP	hp(E)	746 W (exact)	Electric motors, generators, appliances	USA (electrical standards)
Metric HP	hp(M) or PS / CV / ch	735.49875 W	Automotive power (European car specs)	Europe, Latin America, Japan

    💡 Which HP type should I use? For most general purposes —
    comparing car engines, generators, or machinery rated in "hp" — use
    Mechanical HP (745.7 W). For electric motors labelled in hp
    (common on pumps and compressors in the US), use Electrical HP (746 W).
    For European car specs quoting "PS", "CV", or "ch", use Metric HP (735.5 W).
    The difference between all three is less than 1.5%, so for casual estimates any of them work.
  

Horsepower to Watts Conversion Formulas

Each horsepower type has its own exact watt value defined by international standards. All three conversion factors are listed below with worked examples. The mechanical horsepower formula is the most commonly used for engines and general-purpose power ratings.

🔧 Mechanical HP → Watts

watts = hp × 745.699872

Example: 1 hp × 745.699872 = 745.70 W

Example: 10 hp × 745.699872 = 7,456.99 W ≈ 7.457 kW

Example: 200 hp × 745.699872 = 149,139.97 W ≈ 149.14 kW

⚡ Electrical HP → Watts

watts = hp × 746 (exact)

Example: 1 hp(E) × 746 = 746 W

Example: 5 hp(E) × 746 = 3,730 W = 3.730 kW

Example: 50 hp(E) × 746 = 37,300 W = 37.3 kW

🌍 Metric HP → Watts

watts = hp × 735.49875

Example: 1 hp(M) × 735.49875 = 735.50 W

Example: 100 hp(M) × 735.49875 = 73,499.875 W ≈ 73.5 kW

Example: 300 hp(M) × 735.49875 = 220,499.625 W ≈ 220.5 kW

↩️ Watts → Horsepower (Reverse)

hp (mechanical) = watts ÷ 745.699872

hp (electrical) = watts ÷ 746

hp (metric) = watts ÷ 735.49875

Example: 1,000 W ÷ 745.699872 = 1.341 hp (mechanical)

⚡ Quick Reference — Mechanical HP to Watts (Most Common)

1 hp745.7 W

2 hp1,491.4 W

5 hp3,728.5 W

10 hp7,457.0 W

50 hp37,285 W

100 hp74,570 W

200 hp149,140 W

500 hp372,850 W

Horsepower to Watts Conversion Table (All 3 Types)

The comprehensive table below shows mechanical, electrical, and metric horsepower values converted to watts and kilowatts side by side. This is useful when comparing power ratings from different countries or standards — for example, a European car spec in metric HP vs a US engine rating in mechanical HP.

HP Value	Mechanical HP → W	Electrical HP → W	Metric HP → W	Approx. kW
0.5 hp	372.85 W	373.00 W	367.75 W	≈ 0.37 kW
1 hp	745.70 W	746.00 W	735.50 W	≈ 0.75 kW
1.5 hp	1,118.55 W	1,119.00 W	1,103.25 W	≈ 1.12 kW
2 hp	1,491.40 W	1,492.00 W	1,471.00 W	≈ 1.49 kW
3 hp	2,237.10 W	2,238.00 W	2,206.50 W	≈ 2.24 kW
5 hp	3,728.50 W	3,730.00 W	3,677.49 W	≈ 3.73 kW
7.5 hp	5,592.75 W	5,595.00 W	5,516.24 W	≈ 5.59 kW
10 hp	7,457.00 W	7,460.00 W	7,354.99 W	≈ 7.46 kW
15 hp	11,185.50 W	11,190.00 W	11,032.48 W	≈ 11.19 kW
20 hp	14,914.00 W	14,920.00 W	14,709.98 W	≈ 14.91 kW
25 hp	18,642.50 W	18,650.00 W	18,387.47 W	≈ 18.64 kW
50 hp	37,285.00 W	37,300.00 W	36,774.94 W	≈ 37.29 kW
100 hp	74,569.99 W	74,600.00 W	73,549.88 W	≈ 74.57 kW
150 hp	111,854.98 W	111,900.00 W	110,324.81 W	≈ 111.9 kW
200 hp	149,139.97 W	149,200.00 W	147,099.75 W	≈ 149.1 kW
300 hp	223,709.96 W	223,800.00 W	220,649.63 W	≈ 223.7 kW
500 hp	372,849.94 W	373,000.00 W	367,749.38 W	≈ 372.8 kW

Watts to Horsepower Conversion Table

The reverse table below converts common watt and kilowatt values to horsepower. The mechanical HP column is most widely applicable; electrical HP is for motors; metric HP is for European automotive and engineering references.

Watts (W)	Mechanical HP	Electrical HP	Metric HP
100 W	0.1341 hp	0.1340 hp	0.1360 hp
250 W	0.3353 hp	0.3352 hp	0.3399 hp
500 W	0.6705 hp	0.6702 hp	0.6798 hp
746 W	1.0004 hp	1.0000 hp	1.0143 hp
1,000 W (1 kW)	1.3410 hp	1.3405 hp	1.3596 hp
1,500 W	2.0115 hp	2.0107 hp	2.0394 hp
2,000 W (2 kW)	2.6820 hp	2.6810 hp	2.7192 hp
3,000 W (3 kW)	4.0231 hp	4.0214 hp	4.0789 hp
5,000 W (5 kW)	6.7051 hp	6.7024 hp	6.7981 hp
7,500 W (7.5 kW)	10.057 hp	10.054 hp	10.197 hp
10,000 W (10 kW)	13.410 hp	13.405 hp	13.596 hp
15,000 W (15 kW)	20.115 hp	20.107 hp	20.394 hp
37,000 W (37 kW)	49.617 hp	49.598 hp	50.306 hp
75,000 W (75 kW)	100.57 hp	100.54 hp	101.97 hp
100,000 W (100 kW)	134.10 hp	134.05 hp	135.96 hp

When Do You Need to Convert Horsepower to Watts?

The HP-to-watts conversion is needed any time you compare power ratings across different measurement systems — particularly when sourcing equipment from US and European manufacturers, calculating energy costs, or specifying electrical systems.

🚗 Automotive Power Ratings

Car engines in the US are rated in mechanical horsepower (hp), while European and Asian manufacturers often quote both kilowatts (kW) and metric horsepower (PS/CV). A 200 hp US engine = 149.1 kW; a 200 PS (metric hp) European engine = 147.1 kW. Knowing the conversion helps when comparing international car specs, importing vehicles, or reading technical documentation.

🔌 Electric Motors & Pumps

Electric motors on water pumps, air compressors, HVAC units, and industrial machinery in the US are rated in horsepower. A 5 hp motor = 3,730 W = 3.73 kW (electrical hp). This conversion is essential when calculating electricity bills, sizing generators, or selecting inverters for off-grid systems. Motor nameplate data in the US uses hp; European equivalents use kW.

🏍️ Motorcycle & Marine Engines

Motorcycle, outboard motor, and marine engine specifications use hp in the US and kW or PS in Europe. A 100 hp outboard = 74.57 kW (mechanical hp). Marine engineers and boat buyers comparing engines from different countries regularly need this conversion to evaluate performance, fuel efficiency, and electrical load capacity.

☀️ Solar & Renewable Energy

Solar panels, wind turbines, and backup generators are rated in watts or kilowatts. When replacing a diesel generator or engine-driven system rated in hp with a solar or battery system, converting hp to watts helps size the replacement correctly. A 10 hp generator produces approximately 7,457 W = 7.46 kW — so a solar array of at least that size would be needed for a like-for-like replacement.

🏭 Industrial Equipment

Industrial machinery — lathes, mills, conveyors, fans, and compressors — is rated in hp in the US and kW in the rest of the world. Engineers specifying or replacing equipment across different markets need precise hp-to-kW conversion for motor selection, electrical panel sizing, and energy audit calculations. A 50 hp industrial motor = 37.28 kW.

🏠 Home Appliances & HVAC

Air conditioners, vacuum cleaners, lawnmowers, and power tools in the US often quote power in horsepower. A 1 hp central air conditioner compressor = 745.7 W. Converting to watts or kW helps homeowners calculate running costs — at $0.15/kWh, a 1 hp motor running for 8 hours costs approximately $0.90 per day.

✅ HP vs Watts at a Glance: Watts always give a larger number than the same power in horsepower — because one watt is a much smaller unit than one horsepower. So 10 hp = 7,457 W = 7.457 kW. If your watts answer is smaller than your hp input, something is wrong — double-check by multiplying hp × 745.7.

Horsepower & Watts — Key Facts

    📖 Historical Note: The term "horsepower" was coined by Scottish
    engineer James Watt in the 1780s to market his steam engines. He calculated that
    a horse could turn a mill wheel 144 times per hour, and used this to define one
    horsepower as 33,000 foot-pounds of work per minute. Ironically, the SI unit of
    power — the watt — was named after Watt himself, and is now the international
    standard for measuring the same quantity his original horsepower was designed to express.
  

1 mechanical hp = 745.699872 W = 0.745699872 kW
1 electrical hp = 746 W = 0.746 kW (exact, US standard)
1 metric hp (PS/CV/ch) = 735.49875 W = 0.73549875 kW
1 kW = 1.34102 mechanical hp = 1.35962 metric hp
A typical family car engine: 100–200 hp = 75–149 kW
A high-performance sports car: 400–700 hp = 298–522 kW
A standard home refrigerator motor: ≈ 0.1 hp = 74.6 W
A commercial lawnmower engine: ≈ 25 hp = 18.6 kW
A Formula 1 engine (2026): ≈ 1,000 hp = 745.7 kW
James Watt's original mill horse: ≈ 0.5–1 hp ≈ 373–746 W sustained

⚠️ HP Rating vs Actual Output: Engine and motor HP ratings are often given as peak or brake horsepower under ideal conditions, not continuous working output. A 200 hp car engine may only deliver 150 hp to the wheels after drivetrain losses. For electric motors, nameplate HP is the shaft output — the electrical input required is higher due to motor efficiency (typically 85–95%). Always account for efficiency losses when sizing electrical systems based on HP ratings.

Frequently Asked Questions — HP to Watts

How many watts is 1 horsepower?

It depends on the type of horsepower: 1 mechanical (imperial) hp = 745.699872 W; 1 electrical hp = exactly 746 W; 1 metric hp = 735.49875 W. For most general purposes, use 1 hp ≈ 746 W or 0.746 kW. The mechanical hp (745.7 W) is the most commonly used definition for engines and motors in the US.

How do I convert horsepower to watts?

To convert mechanical horsepower to watts, multiply by 745.699872. The formula is: watts = hp × 745.699872. For electrical hp, multiply by 746. For metric hp (PS), multiply by 735.49875. Example: 10 hp (mechanical) × 745.699872 = 7,456.99 W = 7.457 kW. Use the converter at the top of this page to get instant results for all three HP types.

How many hp is 1000 watts (1 kW)?

1,000 watts (1 kW) equals approximately 1.341 mechanical hp, or 1.340 electrical hp, or 1.360 metric hp. So 1 kilowatt is slightly more than 1 horsepower. A quick rule of thumb: 1 kW ≈ 1.34 hp (mechanical). To convert watts to hp, divide by 745.7 for mechanical hp, by 746 for electrical hp, or by 735.5 for metric hp.

What is 100 hp in watts and kilowatts?

100 mechanical hp = 74,569.99 W ≈ 74.57 kW. 100 electrical hp = 74,600 W = 74.6 kW. 100 metric hp = 73,549.88 W ≈ 73.55 kW. This is roughly equivalent to the power output of a small family car. In European specifications, 100 PS (metric hp) ≈ 73.5 kW ≈ 98.6 mechanical hp.

What is the difference between mechanical, electrical, and metric horsepower?

Mechanical (imperial) hp = 745.699872 W — defined as 33,000 foot-pounds per minute, used for engines and pumps in the US. Electrical hp = exactly 746 W — used for electric motors in the US, defined by the NIST. Metric hp (PS/CV/ch) = 735.49875 W — defined as 75 kilogram-force·metres per second, used in European and Asian automotive specs. The three types differ by less than 1.5% from each other.

How many watts is a 200 hp car engine?

A 200 mechanical hp car engine produces 149,139.97 W ≈ 149.14 kW. If the car is rated at 200 metric hp (PS) — common for European cars — the output is 147,099.75 W ≈ 147.1 kW. Note that this is the engine's rated output at the crankshaft; power at the wheels will be lower due to drivetrain losses (typically 10–20%).

How many horsepower is 3000 watts?

3,000 watts equals approximately 4.023 mechanical hp, or 4.021 electrical hp, or 4.079 metric hp. A 3 kW generator is roughly equivalent to a 4 hp engine. This is a common size for small portable generators, water pumps, and workshop machinery. Use the formula: hp = 3000 ÷ 745.699872 = 4.023 hp (mechanical).

Is 1 hp equal to 746 watts exactly?

It depends on the type. Electrical horsepower = exactly 746 W by definition. However, mechanical (imperial) horsepower = 745.699872 W — very close to 746 but not exactly. The difference is less than 0.04%. In everyday use, rounding to 746 W per hp is perfectly acceptable. For precise engineering calculations, use the exact factor for the HP type you are working with.

📚 Helpful Resources

🌐 NIST — Power Unit Definitions

The National Institute of Standards and Technology (NIST) publishes official definitions for horsepower types and their exact watt equivalents, including mechanical hp (745.69987 W) and electrical hp (746 W exactly). NIST is the authoritative US source for all measurement standards in 2026.

Visit NIST →

⚙️ Engineering ToolBox

The Engineering ToolBox provides comprehensive reference data on power units, motor efficiency, and energy conversion factors used in mechanical and electrical engineering. Useful for professionals calculating motor sizing, energy audits, and equipment specification across different measurement systems.

Visit Engineering ToolBox →

🧮 More Free Converters

ConcreteMetric.com offers a growing library of free, accurate unit converters for power, energy, pressure, volume, length, area, time, and more — all fully mobile-friendly and updated for 2026.

Browse All Converters →