Conversion Reference Table
| Unit | Symbol | Equivalent |
|---|---|---|
| Watt (W) | W | SI base unit: 1 J/s |
| Kilowatt (kW) | kW | 1 kW = 1,000 W |
| Megawatt (MW) | MW | 1 MW = 1,000,000 W |
| Horsepower (mech) | hp | 1 hp = 745.7 W |
| Horsepower (metric) | PS | 1 PS = 735.499 W |
| BTU/hour | BTU/hr | 1 BTU/hr = 0.29307 W |
| BTU/minute | BTU/min | 1 BTU/min = 17.584 W |
| kcal/hour | kcal/h | 1 kcal/h = 1.163 W |
| ft·lbf/second | ft·lbf/s | 1 ft·lbf/s = 1.35582 W |
Frequently Asked Questions
What is the difference between mechanical and metric horsepower?
Mechanical (imperial) horsepower (hp) = 745.69987 W. Metric horsepower (PS, from German Pferdestärke) = 735.49875 W — about 1.38% less. Most US car engine ratings use mechanical hp. European and Japanese cars historically used metric PS, though modern specs often use kW.
How many watts does a home use?
A typical US home uses about 1,200–1,500 watts on average (10,500–13,000 kWh/year). Peak demand during summer AC use can exceed 5,000 watts. A single electric vehicle charger (Level 2) adds 7,200–11,500 watts when in use.
What is a gigawatt?
A gigawatt (GW) = 1,000 megawatts = 1,000,000 kilowatts = 1 billion watts. A large nuclear power plant produces about 1 GW. The entire US electrical generating capacity is roughly 1,100 GW. Solar capacity has grown to hundreds of GW globally.
What does a 12,000 BTU/hr air conditioner mean?
12,000 BTU/hr is 1 'ton' of air conditioning capacity — enough to cool roughly 400–600 sq ft. It equals about 3,517 watts or 3.517 kW of cooling power (not the power it draws — actual electricity draw is lower, determined by the EER or SEER rating).