# Convertisseur de puissance

> Convertissez hp en kW, kW en hp, watts en chevaux et BTU/h en tonnes de réfrigération, avec les chevaux mécaniques (745.7 W) et métriques (735.5 W).

Version interactive : https://www.calcopenly.com/fr/conversion/power-converter
Sujet : Convertisseurs d’unités

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.

## Données

- **Valeur**: Un nombre dans l’unité de départ, ou accompagné de sa propre unité
- **De** (options : 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))
- **Vers** (options : 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))

## Résultats

- Valeur convertie — résultat principal
- Conversion
- Facteur de conversion
- Exactitude

## Formule

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

## Exemples détaillés

### 100 hp in kW

- Valeur: 100 hp
- De: horsepower (hp)
- Vers: kilowatt (kW)
- **Valeur convertie: 74.5699871582 kW**
- **Exactitude: Exact**
- Source de vérification : 1 hp = 550 ft·lbf/s = 550 × 0.3048 × 4.4482216152605 W = 745.69987158227022 W (NIST SP 811 App. B)

### 1 kW in hp

- Valeur: 1 kW
- De: kilowatt (kW)
- Vers: horsepower (hp)
- **Valeur convertie: 1.3410220896 hp**
- Source de vérification : 1000 / 745.69987158227022 (Python 3.8 fractions from the legal definitions)

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

- Valeur: 12,000 BTU/h
- De: BTU per hour (BTU/h)
- Vers: ton of refrigeration (TR)
- **Valeur convertie: 1 TR**
- Source de vérification : 1 ton of refrigeration = 12,000 BTU/h (NIST SP 811 App. B)

### Zero power

- Valeur: 0 W
- De: watt (W)
- Vers: horsepower (hp)
- **Valeur convertie: 0 hp**
- **Exactitude: Exact**
- Source de vérification : 0 × any factor = 0

### 1 metric horsepower in watts

- Valeur: 1 PS
- De: metric horsepower (PS)
- Vers: watt (W)
- **Valeur convertie: 735.49875 W**
- Source de vérification : 1 PS = 75 kgf·m/s = 75 × 9.80665 W = 735.49875 W

## Questions

### 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.

### Quelle est la précision de « Convertisseur de puissance » ?

La précision dépend de vos données et des hypothèses de la méthode. Le calcul décimal utilise 50 chiffres significatifs, mais les estimations, méthodes numériques et données sources peuvent être moins précises ; l’arrondi affiché ne supprime pas ces limites. Exemples résolus vérifiés à partir de sources indépendantes : 5. Par exemple, « 100 hp in kW » est vérifié à l’aide de 1 hp = 550 ft·lbf/s = 550 × 0.3048 × 4.4482216152605 W = 745.69987158227022 W (NIST SP 811 App. B).

### D’où vient cette méthode ?

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.

## Sources

- [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)