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Get NordVPN →Power Unit Converter (W, kW, hp, BTU/h)
Type a value, pick the source unit, see all 10 power units side by side. Useful for engines (hp), HVAC (BTU/h), electrical (W/kW), and physics (W/cal/s).
- Watts100
- Kilowatts0.1
- Megawatts0.0001
- Gigawatts0
- Mechanical horsepower (US)0.134102
- Metric horsepower (PS / CV)0.135962
- BTU/hour341.214164
- ft·lb/sec73.756215
- cal/sec23.900574
- kcal/hour86.04223
Power ratings from bulb to reactor
Tap “Use” to load a value into the converter above.
| Item | Value | Equals | |
|---|---|---|---|
| LED bulb | 10 W | 34.12 BTU/h | |
| Laptop charger | 65 W | 221.79 BTU/h | |
| Fit cyclist, sustained effort | 200 W | 172.08 kcal/h | |
| Microwave oven | 800 W | 2,729.71 BTU/h | |
| Electric kettle | 1,500 W | 2.01 hp | |
| One mechanical horsepower | 1 hp | 745.7 W | |
| Home air conditioner (cooling) | 12,000 BTU/h | 3.52 kW | |
| Home EV charger | 7 kW | 9.39 hp | |
| Kei car limit (Japan) | 64 PS | 47.07 kW | |
| Compact car engine | 100 hp | 74.57 kW | |
| Sports car engine | 300 hp | 223.71 kW | |
| Offshore wind turbine | 8 MW | 10,728.18 hp | |
| Nuclear reactor unit | 1 GW | 1,341,022.09 hp |
Related tools
How it works
Power units in everyday life
Watts (W): the SI unit. Used for electrical (LED bulb 9W, microwave 1000W, kitchen kettle 1500W). Defined as 1 joule per second.
Kilowatts (kW) = 1000W: car engines (typical sedan 100-200 kW), home electricity bills, EV charging speed.
Horsepower (hp): two flavors. US/UK 'mechanical hp' = 745.7W. Metric hp (PS in Japan and Germany, CV in France/Spain) = 735.5W. The 1.4% difference matters for car spec sheets — a Japanese 200 PS engine = 197 hp in US units.
BTU/hour (BTU/h): used for air conditioners and heaters in the US. A 12,000 BTU/h AC is about 3.5 kW of cooling power. Confusingly, AC capacity is sometimes also quoted in 'tons' — 1 ton = 12,000 BTU/h.
Common conversions
1 hp (mechanical) ≈ 0.746 kW. So a 100 hp car has ~75 kW.
1 PS (metric hp) ≈ 0.735 kW. A 100 PS car has ~73.5 kW.
1 kW = 3,412 BTU/h. So a 5 kW heater outputs ~17,000 BTU/h.
1 W = 1 J/s. The simplest definition; everything else derives from it.
These are useful to memorize: kW ↔ hp, kW ↔ BTU/h are the most common everyday conversions.
Power vs energy: don't confuse them
Power (W, kW, hp) is rate. Energy (Wh, kWh, J, BTU) is total quantity. A 100W bulb uses 100W of power continuously — over 1 hour, it consumes 100Wh of energy.
Your electricity bill charges per kWh, not per kW. So a 1000W microwave run for 6 minutes uses 100Wh = 0.1 kWh. At ¥30/kWh, that's ¥3.
Cars are a confusing exception: '100 hp engine' is power, but '50 mpg fuel economy' is energy efficiency. Don't mix them up.
Frequently asked questions
›What's the difference between hp and PS?
Mechanical hp (US/UK) = 745.7W. Metric hp / PS / CV (Japan, Germany, France) = 735.5W. About 1.4% smaller. Always check which unit your spec sheet uses for engines.
›Is 1 ton AC cooling = 1 ton of weight?
No relation. '1 ton AC' is the rate that melts 1 ton of ice in 24 hours = 12,000 BTU/h ≈ 3.5 kW. Naming is historical from the era when ice was used for cooling.
›Can I convert kW to kWh?
No — they're different units (power vs energy). To get kWh, multiply kW by hours of operation. A 2 kW heater running for 5 hours uses 10 kWh of energy.
›Why does my electric kettle heat slower than my microwave?
Power difference. A 1000W microwave delivers 1 kW directly to food. A 1500W kettle has more total power but heats 1L of water (which has lots of mass), so it takes time. Power × time = energy.
›What about reactive power vs real power in AC circuits?
This calculator handles only 'real' power (W). Apparent power (VA) and reactive power (VAR) for AC are separate concepts; not covered here.
›How does this work for solar panels?
Panel rated power (e.g., 350W) is peak under standard conditions. Real-world output depends on sun, temperature, and angle. Multiply rated power by your annual sun hours to estimate energy generation (kWh/year).
›What's a 'horsepower' historically?
James Watt defined 1 hp ≈ what a draft horse could sustain (550 ft-lb/s = 745.7W) to market his steam engine in 1782. The number has been stable since.
›Does the data leave my browser?
No. Conversion runs locally; nothing is sent to a server.
Sources & methodology
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