Power Converter
Convert watts, kilowatts, horsepower, BTU/hr and more
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⚡ Power Converter
Convert between power units
Power Conversion Guide
Common Power Conversions
| From | To | Multiply by | Example |
|---|---|---|---|
| Watts | Kilowatts | ÷ 1,000 | 1000 W = 1 kW |
| Kilowatts | Watts | × 1,000 | 1 kW = 1000 W |
| Watts | Horsepower | ÷ 746 | 746 W = 1 HP |
| Horsepower | Watts | × 746 | 1 HP = 746 W |
| Kilowatts | Horsepower | × 1.341 | 1 kW = 1.341 HP |
| Horsepower | Kilowatts | × 0.746 | 1 HP = 0.746 kW |
| Watts | BTU/hour | × 3.412 | 1 W = 3.412 BTU/hr |
| BTU/hour | Watts | ÷ 3.412 | 1 BTU/hr = 0.293 W |
| Kilowatts | BTU/hour | × 3412 | 1 kW = 3412 BTU/hr |
Understanding Power Units
Watt (W)
The watt is the SI unit of power, named after James Watt. One watt equals one joule per second. It's the standard unit for measuring electrical power consumption.
Common uses: Light bulbs (60W), phone chargers (5-20W), laptop power consumption (45-100W)
Kilowatt (kW)
A kilowatt is 1,000 watts. It's commonly used for larger appliances and electrical systems.
Common uses: Home heating (3-5 kW), electric cars (50-200 kW), home electricity usage (measured in kWh)
Megawatt (MW)
A megawatt is 1,000,000 watts or 1,000 kilowatts. Used for large-scale power generation and industrial applications.
Common uses: Wind turbines (2-8 MW), data centers (5-50 MW), small power plants (10-100 MW)
Horsepower (HP)
Mechanical horsepower (HP) was developed by James Watt to compare steam engines to horses. One HP = 746 watts.
Common uses: Car engines (100-500 HP), lawn mowers (3-7 HP), industrial motors
Metric Horsepower (PS)
PS (Pferdestärke) is slightly different from mechanical HP. One PS = 735.5 watts, making it about 1.4% less than mechanical HP.
Common uses: European car specs, motorcycles
BTU/hour
British Thermal Units per hour measures heating/cooling capacity. One BTU/hr = 0.293 watts.
Common uses: Air conditioners (6,000-24,000 BTU/hr), furnaces (40,000-100,000 BTU/hr)
Power Examples by Scale
| Device/System | Typical Power | In Different Units |
|---|---|---|
| LED Light Bulb | 10 W | 0.01 kW / 0.013 HP / 34 BTU/hr |
| Laptop Computer | 65 W | 0.065 kW / 0.087 HP / 222 BTU/hr |
| Microwave Oven | 1,000 W | 1 kW / 1.34 HP / 3,412 BTU/hr |
| Hair Dryer | 1,500 W | 1.5 kW / 2 HP / 5,118 BTU/hr |
| Home AC Unit | 3,500 W | 3.5 kW / 4.7 HP / 12,000 BTU/hr |
| Electric Car Motor | 75,000 W | 75 kW / 100 HP / 256,000 BTU/hr |
| Compact Car Engine | 100 HP | 75 kW / 255,000 BTU/hr |
| Sports Car Engine | 400 HP | 298 kW / 1,020,000 BTU/hr |
| Wind Turbine | 2,000 kW | 2 MW / 2,682 HP / 6,824,000 BTU/hr |
Power vs Energy
Important distinction: Power is the rate of energy use, not the total energy.
- ⚡ Power (Watts): How fast energy is used
- 🔋 Energy (Watt-hours): Total energy consumed over time
- 📊 Example: A 100W light bulb running for 10 hours uses 1,000 Wh (1 kWh) of energy
- 💡 Formula: Energy (Wh) = Power (W) × Time (hours)
Electricity Bill Calculation
Your electricity bill is based on kilowatt-hours (kWh), not just kilowatts:
- 1 kW appliance running for 1 hour = 1 kWh
- 100 W light bulb running for 10 hours = 1 kWh
- Average US electricity cost: $0.16 per kWh
- 1,500 W space heater running 8 hours/day = 12 kWh/day = $1.92/day
Automotive Power Ratings
Why cars use horsepower: Historical tradition from comparing to horse-drawn carriages. Modern equivalents:
- 🚗 Economy Car: 100-130 HP (75-97 kW)
- 🚙 Mid-size Sedan: 150-200 HP (112-149 kW)
- 🏎️ Sports Car: 300-500 HP (224-373 kW)
- 🏁 Supercar: 500-1000+ HP (373-746+ kW)
- 🚛 Semi Truck: 400-600 HP (298-447 kW)
HVAC and Climate Control
Air conditioner ratings: Usually given in BTU/hr or tons of cooling:
- ❄️ 1 Ton of cooling = 12,000 BTU/hr = 3.52 kW
- 🏠 Small room AC: 5,000-8,000 BTU/hr (1.5-2.3 kW)
- 🏘️ Large room AC: 12,000-18,000 BTU/hr (3.5-5.3 kW)
- 🏢 Whole house AC: 2-5 tons (24,000-60,000 BTU/hr)
Renewable Energy
Solar and wind power ratings:
- ☀️ Residential solar panel: 250-400 W each
- 🏠 Home solar system: 4-10 kW (16-40 panels)
- 💨 Home wind turbine: 2-10 kW
- 🌊 Offshore wind turbine: 2-8 MW
- ⚡ Hoover Dam: 2,080 MW total capacity
Frequently Asked Questions
How do I convert horsepower to watts?
Multiply horsepower by 746. For example: 100 HP × 746 = 74,600 watts (or 74.6 kW). One mechanical horsepower equals exactly 745.7 watts, commonly rounded to 746.
What's the difference between horsepower (HP) and metric horsepower (PS)?
Mechanical HP (used in USA) = 746 watts, while metric HP or PS (Pferdestärke, used in Europe) = 735.5 watts. PS is about 1.4% less powerful than HP. A 100 HP engine is approximately 101.4 PS.
How many watts is 1 horsepower?
One mechanical horsepower equals 746 watts or 0.746 kilowatts. Conversely, 1 kilowatt equals approximately 1.341 horsepower.
What's the difference between watts and watt-hours?
Watts (W) measure power - the rate of energy use. Watt-hours (Wh) measure energy - the total amount used over time. Think of it like miles per hour vs. total miles traveled. A 100W bulb running for 10 hours uses 1,000 Wh (1 kWh) of energy.
How many BTU/hr equals 1 ton of cooling?
One ton of cooling equals 12,000 BTU/hr or approximately 3.52 kW. The term "ton" comes from the cooling power needed to melt one ton of ice in 24 hours.
Why do European cars use kW instead of HP?
Europe has largely adopted the metric system's kilowatt (kW) as the standard power rating. The EU requires kW to be shown, though HP (or PS) is often listed too. 1 kW = 1.341 HP. A 100 kW engine equals approximately 134 HP.
How much does it cost to run a 1,500W heater?
At the US average electricity rate of $0.16/kWh: 1,500W = 1.5 kW. Running 1 hour = 1.5 kWh = $0.24. Running 8 hours/day = 12 kWh = $1.92/day or about $57/month.
Power Conversion Formulas
Quick reference formulas:
- Watts = Horsepower × 746
- Horsepower = Watts ÷ 746
- Kilowatts = Horsepower × 0.746
- Horsepower = Kilowatts × 1.341
- BTU/hr = Watts × 3.412
- Watts = BTU/hr ÷ 3.412
- kWh (energy) = kW (power) × hours