P_W — Power in Watts (W)
P_kW — Power in Kilowatts (kW)
P_HP — Power in Horsepower (HP)
P_BTU/h — Power in British Thermal Units per hour (BTU/h)
P_kcal/h — Power in Kilocalories per hour (kcal/h)
A tool for converting between common power units such as Watt (W), Kilowatt (kW), Horsepower (HP), BTU/h, and kcal/h.
This calculator allows you to convert power values between different units used in electrical engineering, HVAC systems, and automotive applications. Input one value, and all others are automatically calculated.
| Unit | Full Name | Relation to Watt (W) |
|---|---|---|
| W | Watt | 1 W = 1 W |
| kW | Kilowatt | 1 kW = 1000 W |
| HP | Horsepower | 1 HP ≈ 745.7 W (mechanical) 1 HP ≈ 735.5 W (metric) |
| BTU/h | British Thermal Unit per hour | 1 BTU/h ≈ 0.000293071 W 1 W ≈ 3.600 BTU/h |
| kcal/h | Kilocalorie per hour | 1 kcal/h ≈ 1.163 W 1 W ≈ 0.8598 kcal/h |
An air conditioner has a cooling capacity of 3000 kcal/h
Then power:
P = 3000 × 1.163 ≈ 3489 W
Or about 3.49 kW
Engine output power is 200 HP (mechanical)
Then:
P = 200 × 745.7 = 149,140 W ≈ 149.14 kW
Heating power is 5 kW
Then:
- BTU/h = 5 × 3600 = 18,000 BTU/h
- kcal/h = 5 × 859.8 ≈ 4299 kcal/h
1. Motor and generator selection
2. HVAC system design
3. Automotive engine power rating
4. Energy efficiency evaluation
5. Academic learning and exams
Metric horsepower (PS) is approximately 735.5 W, while mechanical horsepower (HP) is approximately 745.7 W, a difference of about 1.4%. Metric horsepower is commonly used in Europe and Japan, while mechanical horsepower is used in the UK and US. It is important to distinguish between them in engineering calculations, as confusion may lead to approximately 1.4% error.
kcal/h and BTU/h are heat units that directly represent the thermal exchange capacity of cooling or heating, which aligns better with HVAC industry conventions. While Watts (W) are power units and can be converted, they are less intuitive in the HVAC field. This calculator supports real-time conversion among all three units for different application scenarios.
1 kW = 3600 BTU/h. This is because 1 W ≈ 3.6 BTU/h, so 1000 W × 3.6 = 3600 BTU/h. For example, a 5 kW electric heater has a heat output of 5 × 3600 = 18,000 BTU/h.
It is commonly used for motor and generator selection (kW to HP conversion), HVAC system design (kW to kcal/h and BTU/h conversion), automotive engine power rating, energy efficiency evaluation, and academic learning and exams in physics and engineering.
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