# 功率单位换算器

> 换算 hp 与 kW、瓦特与马力，以及 BTU/h 与冷吨，区分机械马力（745.7 W）和公制马力（735.5 W）。

交互版本：https://www.calcopenly.com/zh/conversion/power-converter
主题：单位换算器

Every power unit is a fixed number of watts (joules per second). Mechanical horsepower is 550 foot-pounds-force per second, which works out at exactly 745.69987158227022 W; metric horsepower (PS) is 75 kilogram-force metres per second, exactly 735.49875 W. A ton of refrigeration is 12,000 BTU/h, about 3.517 kW.

The default converts a 100 hp engine to 74.57 kW. Car specifications are the usual reason: European registration documents give engine power in kW while brochures quote PS or hp, and 100 kW is 134.1 hp or 136.0 PS.

Air-conditioner ratings in BTU/h or tons describe cooling output, not the electricity drawn: a 1.5-ton unit moves 18,000 BTU/h (5.28 kW) of heat, and its electrical input depends on its efficiency rating.

## 输入

- **数值**: 输入源单位下的数值，也可以输入带有自身单位的数值
- **从** (选项：watt (W), milliwatt (mW), kilowatt (kW), megawatt (MW), gigawatt (GW), horsepower (hp), metric horsepower (PS), BTU per hour (BTU/h), ton of refrigeration (TR), kilocalorie per hour (kcal/h))
- **到** (选项：watt (W), milliwatt (mW), kilowatt (kW), megawatt (MW), gigawatt (GW), horsepower (hp), metric horsepower (PS), BTU per hour (BTU/h), ton of refrigeration (TR), kilocalorie per hour (kcal/h))

## 结果

- 转换后的数值 — 主要结果
- 换算
- 换算系数
- 精确性

## 公式

$$
\begin{gathered} x_{\text{to}} = x_{\text{from}} \times \dfrac{f_{\text{from}}}{f_{\text{to}}} \\ f = \text{one unit expressed in } \text{W} \end{gathered}
$$

## 计算示例

### 100 hp in kW

- 数值: 100 hp
- 从: horsepower (hp)
- 到: kilowatt (kW)
- **转换后的数值: 74.5699871582 kW**
- **精确性: 精确**
- 核验来源：1 hp = 550 ft·lbf/s = 550 × 0.3048 × 4.4482216152605 W = 745.69987158227022 W (NIST SP 811 App. B)

### 1 kW in hp

- 数值: 1 kW
- 从: kilowatt (kW)
- 到: horsepower (hp)
- **转换后的数值: 1.3410220896 hp**
- 核验来源：1000 / 745.69987158227022 (Python 3.8 fractions from the legal definitions)

### 12,000 BTU/h is one ton of refrigeration

- 数值: 12,000 BTU/h
- 从: BTU per hour (BTU/h)
- 到: ton of refrigeration (TR)
- **转换后的数值: 1 TR**
- 核验来源：1 ton of refrigeration = 12,000 BTU/h (NIST SP 811 App. B)

### Zero power

- 数值: 0 W
- 从: watt (W)
- 到: horsepower (hp)
- **转换后的数值: 0 hp**
- **精确性: 精确**
- 核验来源：0 × any factor = 0

### 1 metric horsepower in watts

- 数值: 1 PS
- 从: metric horsepower (PS)
- 到: watt (W)
- **转换后的数值: 735.49875 W**
- 核验来源：1 PS = 75 kgf·m/s = 75 × 9.80665 W = 735.49875 W

## 常见问题

### How many watts are in a horsepower?

745.7 W for mechanical horsepower (550 ft·lbf/s), 735.5 W for metric horsepower (PS or CV), and exactly 746 W for the electric horsepower used to rate electric motors; NIST SP 811 lists all three. Mechanical and metric horsepower differ by 1.4%, enough to matter when comparing car figures.

### How do I convert kW to hp?

Multiply by 1.34102 for mechanical horsepower or by 1.35962 for metric PS. A 150 kW engine is 201.2 hp or 203.9 PS. To go from hp to kW, multiply by 0.7457, so the default 100 hp is 74.57 kW.

### What is the difference between hp, bhp and PS?

hp and bhp use the same 745.7 W unit; “brake” horsepower means the power was measured at the engine's output shaft, before transmission losses. PS (Pferdestärke) is metric horsepower, 735.5 W, also written CV or ch. A car quoted at 150 PS makes 147.9 hp or 110.3 kW.

### What does a 1.5-ton air conditioner mean?

It removes 18,000 BTU of heat per hour, which is 5.28 kW of cooling. A ton of refrigeration is 12,000 BTU/h, the rate that melts one short ton (2,000 lb) of ice in 24 hours, because ice absorbs 144 BTU per pound as it melts. The electricity it draws is lower and depends on its efficiency rating.

### How many BTU/h is 1 kW?

3,412.14 BTU/h. One watt is 3.41214 BTU/h, so a 2 kW electric heater gives out 6,824 BTU/h, and a 12,000 BTU/h air conditioner is rated at 3.517 kW of cooling. The factor is the same as between kWh and BTU because both sides are divided by one hour.

### “功率单位换算器”有多准确？

准确性取决于输入值和方法的假设。十进制运算使用50位有效数字，但估算、数值方法和源数据的精度可能较低；显示时的舍入并不能消除这些限制。 已按独立来源核验的计算示例：5。 例如，“100 hp in kW”根据1 hp = 550 ft·lbf/s = 550 × 0.3048 × 4.4482216152605 W = 745.69987158227022 W (NIST SP 811 App. B)进行核验。

### 这种方法出自哪里？

NIST SP 811 (2008), Guide for the Use of the SI, Appendix B — conversion factors; NIST Handbook 44, Appendix C — General tables of units of measurement.

## 来源

- [NIST SP 811 (2008), Guide for the Use of the SI, Appendix B — conversion factors](https://www.nist.gov/pml/special-publication-811)
- [NIST Handbook 44, Appendix C — General tables of units of measurement](https://www.nist.gov/pml/owm/nist-handbook-44-current-edition)