Watts ↔ Horsepower Converter
⚡ Watts to Horsepower
🐴 Horsepower to Watts
Quick Conversions
Common Power Examples
🚗 Economy Car Engine
Typical power: 75–120 HP (56–90 kW)
🏎️ Sports Car Engine
Typical power: 300–500 HP (224–373 kW)
🔌 Electric Motor (Small)
Typical power: 0.5–2 HP (373–1,492 W)
🌀 HVAC Blower Motor
Typical power: 0.25–1 HP (186–746 W)
🧹 Vacuum Cleaner
Typical power: 1–2.5 HP (746–1,865 W)
🚜 Lawn Mower
Typical power: 3–7 HP (2.2–5.2 kW)
🏊 Pool Pump
Typical power: 0.75–2 HP (560–1,492 W)
🏭 Industrial Motor
Typical power: 10–500 HP (7.5–373 kW)
Horsepower Types Explained
There are three main horsepower standards, each with a slightly different watt equivalent. The differences arose from historical and regional measurement systems.
Mechanical (Imperial) HP
Metric HP (PS/CV/pk)
Electrical HP
Conversion Formulas
Watts to HP:
Mechanical HP = Watts ÷ 745.699872
Metric HP (PS) = Watts ÷ 735.49875
Electrical HP = Watts ÷ 746
HP to Watts:
Watts = Mechanical HP × 745.699872
Watts = Metric HP × 735.49875
Watts = Electrical HP × 746
Reference Table: Watts to Horsepower
| Watts | Mechanical HP | Metric HP (PS) | kW |
|---|---|---|---|
| 100 W | 0.134 | 0.136 | 0.1 |
| 250 W | 0.335 | 0.340 | 0.25 |
| 500 W | 0.671 | 0.680 | 0.5 |
| 746 W | 1.000 | 1.014 | 0.746 |
| 1,000 W | 1.341 | 1.360 | 1.0 |
| 1,500 W | 2.012 | 2.039 | 1.5 |
| 2,000 W | 2.682 | 2.719 | 2.0 |
| 3,000 W | 4.023 | 4.079 | 3.0 |
| 5,000 W | 6.705 | 6.798 | 5.0 |
| 7,500 W | 10.058 | 10.197 | 7.5 |
| 10,000 W | 13.410 | 13.596 | 10.0 |
Reference Table: Horsepower to Watts
| Horsepower | Watts (Mech.) | Watts (Metric) | kW (Mech.) |
|---|---|---|---|
| 0.5 HP | 373 W | 368 W | 0.37 |
| 1 HP | 746 W | 736 W | 0.75 |
| 1.5 HP | 1,119 W | 1,103 W | 1.12 |
| 2 HP | 1,491 W | 1,471 W | 1.49 |
| 3 HP | 2,237 W | 2,207 W | 2.24 |
| 5 HP | 3,728 W | 3,677 W | 3.73 |
| 7.5 HP | 5,593 W | 5,516 W | 5.59 |
| 10 HP | 7,457 W | 7,355 W | 7.46 |
| 15 HP | 11,185 W | 11,032 W | 11.19 |
| 20 HP | 14,914 W | 14,710 W | 14.91 |
| 25 HP | 18,642 W | 18,387 W | 18.64 |
| 50 HP | 37,285 W | 36,775 W | 37.28 |
| 100 HP | 74,570 W | 73,550 W | 74.57 |
History of Horsepower
Horsepower was invented by Scottish engineer James Watt in the late 1780s to market his improved steam engines. He needed a way to compare engine output to the work done by draft horses, which were the primary power source at the time.
Watt observed horses at a mine and estimated that a typical horse could lift 550 pounds one foot in one second (or 33,000 foot-pounds per minute). This became the definition of one mechanical horsepower.
Today, the watt (named after James Watt himself) is the SI unit of power. One watt equals one joule per second. For most scientific and engineering applications, kilowatts (kW) are preferred over horsepower due to their precise definition.
When to Use Each HP Type
- Mechanical HP: Use for US/UK vehicle specifications, American-made motors, and most English-language technical documents.
- Metric HP (PS/CV): Use for European car specifications, particularly German (PS = Pferdestärke), French and Italian (CV = cheval-vapeur), and Dutch (pk = paardenkracht) documents.
- Electrical HP: Use specifically for electric motor nameplate ratings in North America. Motors are often sold in standard HP sizes (1/4, 1/3, 1/2, 3/4, 1, 1.5, 2, 3, 5 HP, etc.).
Note: Electric vehicles (EVs) typically specify power in kilowatts (kW) rather than horsepower, though marketing materials may convert to HP for consumer familiarity.
Frequently Asked Questions
How many watts are in one horsepower?
One mechanical (imperial) horsepower equals 745.7 watts. One metric horsepower equals 735.5 watts. One electrical horsepower equals exactly 746 watts.
What is the difference between mechanical and metric horsepower?
Mechanical horsepower (hp) is the imperial standard equal to 745.7 watts. Metric horsepower (PS or CV) equals 735.5 watts. The difference is about 1.4%. European car specs often use metric HP, which is why a car might be listed as "150 PS" in Germany but "148 hp" in the US.
How do I convert 1500 watts to horsepower?
Divide 1500 by the horsepower factor: 1500 ÷ 745.7 = 2.01 mechanical HP, or 1500 ÷ 735.5 = 2.04 metric HP.
How many watts is a 1 HP motor?
A 1 HP electric motor is rated at 746 watts (electrical horsepower standard). However, actual power consumption depends on motor efficiency—modern motors are typically 80-95% efficient.
Why do cars list different HP values in different countries?
US and UK markets use mechanical horsepower, while European markets often use metric horsepower (PS/CV). A 100 hp (mechanical) car is approximately 101.4 PS (metric). Always check which standard is being used when comparing specs.
What is brake horsepower (BHP)?
Brake horsepower measures engine output at the flywheel before losses from the transmission and drivetrain. It's measured using a dynamometer (or "brake"). BHP uses the same watt conversion as mechanical HP (745.7 W).
Is kW or HP more accurate?
Kilowatts are more precise because they're based on the SI system with exact definitions. Horsepower varies slightly by type (mechanical, metric, electrical). For technical specifications, engineers prefer kW.
How do I convert kW to HP?
Multiply kilowatts by 1.341 for mechanical HP, or by 1.360 for metric HP. Example: 100 kW × 1.341 = 134.1 mechanical HP.
Privacy & Limitations
- All calculations run entirely in your browser -- nothing is sent to any server.
- Results are estimates and may vary based on actual conditions.
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This tool FAQ
How many watts are in one horsepower?
One mechanical (imperial) horsepower equals 745.7 watts. One metric horsepower equals 735.5 watts. One electrical horsepower equals exactly 746 watts.
What is the difference between mechanical and metric horsepower?
Mechanical horsepower (hp) is the imperial standard equal to 745.7 watts. Metric horsepower (PS or CV) equals 735.5 watts. The difference is about 1.4%. European car specs often use metric HP.
How do I convert watts to horsepower?
Divide watts by 745.7 for mechanical horsepower, by 735.5 for metric horsepower, or by 746 for electrical horsepower. Example: 1500W ÷ 745.7 = 2.01 hp (mechanical).
How do I convert horsepower to watts?
Multiply horsepower by 745.7 for mechanical hp, by 735.5 for metric hp, or by 746 for electrical hp. Example: 5 hp × 745.7 = 3728.5 watts.
Why are there different types of horsepower?
Different horsepower standards evolved historically. James Watt defined mechanical horsepower in the 1780s. Metric horsepower was later standardized in Europe. Electrical horsepower (746W exactly) was defined for electric motors.
What horsepower type do cars use?
US and UK cars typically use mechanical horsepower (hp). European cars often use metric horsepower (PS in Germany, CV in France/Italy). Japanese cars may use either depending on the market.
How many watts is a 1 HP motor?
A 1 HP electric motor draws approximately 746 watts (electrical horsepower standard). However, the actual power consumption depends on motor efficiency, typically 80-95% for modern motors.
Is kW or HP more accurate?
Kilowatts (kW) are more precise because they're based on the SI system with exact definitions. Horsepower varies by type (mechanical, metric, electrical). For technical specifications, kW is preferred.