Horsepower to Watts Converter — hp to W

The Conversion: 1 Horsepower = 745.7 Watts

One mechanical (imperial) horsepower equals 745.7 watts. To convert horsepower to watts, multiply by 745.7. This is the standard horsepower used for engines, motors, and machinery in the US and UK.

• Horsepower → Watts: Multiply by 745.7 (e.g., 5 hp × 745.7 = 3,728.5 W)
• Horsepower → Kilowatts: Multiply by 0.7457 (e.g., 200 hp × 0.7457 = 149.1 kW)

Quick mental estimate: 1 hp ≈ ¾ kilowatt (750 W). For fast arithmetic: multiply hp by 750. A 100 hp engine ≈ 75,000 W = 75 kW. A 200 hp engine ≈ 150 kW. This approximation is accurate to within 0.6% — close enough for quick estimates.

Note on horsepower variants: Mechanical hp = 745.7 W (this converter). Metric horsepower (PS/CV) = 735.5 W. Electrical hp = 746 W exactly. Boiler hp = 9,810 W. Always check which type is referenced when comparing specifications across regions.

Horsepower to Watts Conversion Table

Common horsepower ratings converted to watts and kilowatts, with practical context:

Electric Vehicles: From Horsepower to Kilowatts

The automotive world is transitioning from horsepower to kilowatts as electric vehicles (EVs) become mainstream. Understanding the hp-to-watts conversion is essential for comparing conventional and electric vehicles.

Why EVs use kW: Electric motor specifications are natively in watts and kilowatts. While manufacturers still advertise horsepower for marketing purposes in the US, the engineering specs, charging rates, and efficiency calculations are all in kW. European regulations already require kW for official vehicle specifications — the EU type approval system uses kW exclusively.

Notable EV power ratings:

• Nissan Leaf (base): 110 kW = 147 hp — affordable urban commuter
• Tesla Model 3 Standard Range: 208 kW = 279 hp — mainstream EV benchmark
• BMW iX xDrive50: 385 kW = 516 hp — luxury electric SUV
• Porsche Taycan Turbo S: 560 kW = 751 hp — high-performance electric sports car
• Rimac Nevera: 1,408 kW = 1,888 hp — electric hypercar, fastest production EV
• Tesla Semi: ~746 kW = ~1,000 hp — electric commercial truck

Charging power vs. motor power: Don't confuse motor power (hp/kW) with charging power. A Tesla Model 3 has a 258 kW (346 hp) motor but accepts only up to 250 kW from a Supercharger. A home Level 2 charger provides 7.2–19.2 kW — enough to add 25–65 miles of range per hour, but a tiny fraction of the motor's output power. The battery acts as the buffer between low-power charging and high-power driving.

Efficiency comparison: A gasoline engine converts about 20–35% of fuel energy into mechanical power. An electric motor converts 85–95% of electrical energy into mechanical power. This means a 150 kW (201 hp) electric motor does the work of a roughly 300–400 hp gasoline engine when measured from energy input to wheels. This efficiency advantage is why a seemingly less powerful EV can match or outperform a higher-hp gas car in real-world driving.

Power Tools and Workshop Equipment

Woodworkers, metalworkers, and DIY enthusiasts encounter horsepower ratings on every major power tool. Converting to watts helps estimate circuit requirements and compare tools rated in different units.

• Circular saw: 10–15 amps at 120V = 1,200–1,800 W = 1.6–2.4 hp. Most consumer models are around 2 hp.
• Table saw: Entry-level: 1.5 hp (1,119 W). Cabinet saw: 3–5 hp (2,237–3,729 W). Industrial: 5–7.5 hp (3,729–5,593 W).
• Router: Trim router: 1–1.25 hp (746–932 W). Plunge router: 2–3.25 hp (1,491–2,423 W). The higher-hp routers can handle larger bits and harder woods without bogging down.
• Drill press: Benchtop: ⅓–½ hp (246–373 W). Floor-standing: ¾–1.5 hp (559–1,119 W). Industrial: 1–3 hp (746–2,237 W).
• Air compressor: Pancake (portable): 0.5–1 hp (373–746 W). Shop compressor: 2–5 hp (1,491–3,729 W). Professional: 5–10 hp (3,729–7,457 W).

Circuit sizing: Knowing the watt equivalent of horsepower helps determine electrical requirements. A standard US 15-amp, 120V circuit provides 1,800 watts (2.4 hp). A 20-amp circuit provides 2,400 watts (3.2 hp). Heavy tools like cabinet table saws (3–5 hp) often require a dedicated 240V circuit: a 20-amp 240V circuit provides 4,800 watts (6.4 hp).

When a tool draws more power than the circuit can supply, the breaker trips. This is why a 3 hp table saw (2,237 W continuous, with startup surge of 3,000+ W) frequently trips a 15-amp 120V breaker (1,800 W capacity). The solution is either a 20-amp circuit, a 240V circuit, or a soft-start module that reduces the startup surge. Understanding the hp-to-watts conversion makes these electrical decisions straightforward.

Cordless tool batteries: Modern cordless tools use lithium-ion batteries rated in volt-ampere-hours. A DeWalt 20V Max 5Ah battery stores 100 Wh. A cordless circular saw drawing 1,500 W (2 hp) from this battery would drain it in about 4 minutes of continuous cutting — which is why cordless tools cycle on and off, and why corded tools are still preferred for sustained heavy-duty work.

Marine and Boat Engines

Boat motors are almost universally rated in horsepower, but understanding the watt equivalent matters for comparing outboard engines, electric boat motors, and calculating fuel consumption.

The marine industry is beginning to adopt electric propulsion. Electric outboard motors from companies like Torqeedo, ePropulsion, and Flux Marine are rated in both kW and hp equivalent. A Torqeedo Cruise 10.0 produces 10 kW (13.4 hp) — equivalent to a 20+ hp gas outboard in terms of actual thrust because electric motors deliver torque more efficiently through the propeller. The 2:1 "equivalent" ratio is a rough industry guideline: an electric motor produces similar real-world performance to a gas motor of roughly twice the horsepower rating.

For sailboat auxiliary engines, a common rule of thumb is 3–4 hp per ton of displacement. A 10,000 lb (4.5 ton) sailboat needs about 13.5–18 hp (10.1–13.4 kW) for adequate motoring. An electric conversion with a 10 kW motor (13.4 hp) and a 10 kWh battery bank provides about 1 hour at full power — enough for harbor maneuvering but not extended cruising. Larger battery banks (20–50 kWh) extend this range proportionally.

Agriculture and Heavy Equipment

Tractors, combines, and agricultural equipment are rated in horsepower, making it one of the most important specs for farmers and equipment operators. The watt equivalent matters for comparing diesel, gas, and emerging electric agricultural machinery.

• Garden tractor: 15–25 hp (11.2–18.6 kW). Lawn mowing, light towing, small attachments.
• Compact tractor: 25–50 hp (18.6–37.3 kW). Hobby farms, landscape maintenance, small acreage.
• Utility tractor: 50–100 hp (37.3–74.6 kW). General farming, hay operations, mid-size implements.
• Row crop tractor: 100–250 hp (74.6–186.4 kW). Field cultivation, planting, spraying.
• 4WD tractor: 250–600 hp (186.4–447.4 kW). Large-scale farming, heavy tillage.
• Combine harvester: 200–600 hp (149.1–447.4 kW). Grain harvesting, specialty crops.

PTO horsepower: Farm equipment uses Power Take-Off (PTO) horsepower — the power available at the tractor's PTO shaft to drive implements like mowers, balers, and augers. PTO hp is typically 80–85% of engine hp due to drivetrain losses. A tractor with 100 engine hp delivers about 80–85 PTO hp (59.7–63.4 kW). When a hay baler requires "50 PTO hp minimum," you need a tractor with at least 59–63 engine hp to drive it properly.

Electric tractors are emerging in the agricultural market. Monarch Tractor's MK-V produces 70 hp (52 kW) from an electric drivetrain with a 196 kWh battery, providing 10+ hours of operation for many tasks. John Deere's prototype electric tractor delivers 500 kW (670 hp) for heavy fieldwork. The advantage of electric in agriculture: instant full torque at low speeds (ideal for heavy pulling), lower operating costs ($2–4/hour for electricity vs. $15–30/hour for diesel), and zero emissions — increasingly important as environmental regulations tighten on farm operations.

Renewable Energy: Wind and Solar Power

Understanding horsepower in the context of renewable energy helps bridge traditional power concepts with modern clean energy systems.

Wind turbines: Modern utility-scale wind turbines generate 2–15 MW (2,682–20,114 hp). A single 5 MW turbine produces 6,706 hp — equivalent to about 50 mid-range car engines running continuously. A large wind farm with 100 turbines at 5 MW each produces 500 MW (670,571 hp), enough to power approximately 350,000 homes.

Solar panels: A standard residential solar panel produces 350–400 W (0.47–0.54 hp) under peak sunlight. A typical 8 kW home solar array (20 panels) produces 10.7 hp at peak — roughly equivalent to a small tractor engine. Over a full day in a sunny climate, this array might generate 30–40 kWh (40.2–53.6 hp-hours) — enough to charge an electric car for 100+ miles of driving.

Perspective: The average US household uses about 30 kWh per day = 40.2 hp-hours. That's like running a 1.67 hp motor 24 hours a day. Or, equivalently, keeping a horse working continuously at 70% capacity all day and night. Before electricity, this much sustained power was genuinely difficult to achieve — multiple horses, a water wheel, or a small steam engine would have been required. Today, a modest rooftop solar installation provides it silently and for free (after installation costs).

Energy storage: Battery systems are rated in kWh (energy) and kW (power). A Tesla Powerwall stores 13.5 kWh and delivers up to 7 kW (9.4 hp) continuous or 10 kW (13.4 hp) peak. A larger commercial battery system might store 1 MWh and deliver 500 kW (670 hp) — enough to power a small industrial facility during a grid outage or peak pricing period.