# Convertisseur de fréquence

> Convert rpm to Hz, Hz to rpm, BPM to Hz, GHz to MHz and hertz to radians per second (ω = 2πf), from Hz to THz.

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

One hertz is one cycle per second, so revolutions per minute and beats per minute divide by 60 to give hertz, and the SI prefixes step by 1,000 from kHz to THz. Angular frequency in radians per second is ω = 2πf, so 1 Hz is 6.2832 rad/s; conversions to or from rad/s involve π and are shown to 12 significant figures.

The default converts 3,000 rpm to 50 Hz, the speed of a two-pole motor on a 50 Hz supply. Musicians convert tempo the same way (120 BPM is 2 Hz), and radio users move between MHz and GHz: 2.4 GHz Wi-Fi is 2,400 MHz.

Rpm and BPM count whole cycles per minute, while rad/s counts the angle swept per second. A cycle is 2π radians, so 60 rpm is 1 Hz and 6.2832 rad/s.

## Données

- **Valeur**: Un nombre dans l’unité de départ, ou accompagné de sa propre unité
- **De** (options : hertz (Hz), kilohertz (kHz), megahertz (MHz), gigahertz (GHz), terahertz (THz), revolution per minute (rpm), beat per minute (BPM), radian per second (rad/s))
- **Vers** (options : hertz (Hz), kilohertz (kHz), megahertz (MHz), gigahertz (GHz), terahertz (THz), revolution per minute (rpm), beat per minute (BPM), radian per second (rad/s))

## Résultats

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

## Formule

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

## Exemples détaillés

### 3000 rpm in Hz

- Valeur: 3000 rpm
- De: revolution per minute (rpm)
- Vers: hertz (Hz)
- **Valeur convertie: 50 Hz**
- Source de vérification : 3000 / 60 = 50

### 120 BPM in Hz

- Valeur: 120 BPM
- De: beat per minute (BPM)
- Vers: hertz (Hz)
- **Valeur convertie: 2 Hz**
- Source de vérification : 120 / 60 = 2

### 1 Hz in rad/s

- Valeur: 1 Hz
- De: hertz (Hz)
- Vers: radian per second (rad/s)
- **Valeur convertie: 6.2831853072 rad/s**
- **Exactitude: Définitions exactes, fait intervenir π**
- Source de vérification : ω = 2πf = 6.28318530717958647… (Python decimal)

### 2.4 GHz in MHz

- Valeur: 2.4 GHz
- De: gigahertz (GHz)
- Vers: megahertz (MHz)
- **Valeur convertie: 2,400 MHz**
- Source de vérification : 2.4 × 1000

## Questions

### How do I convert rpm to Hz?

Divide by 60, because hertz counts cycles per second and rpm cycles per minute. 3,000 rpm is 50 Hz, 1,800 rpm is 30 Hz, and 7,200 rpm, a common hard-drive speed, is 120 Hz. To go from Hz to rpm, multiply by 60.

### Why does a motor run at 3,000 or 3,600 rpm?

Because its speed is locked to the supply frequency. A synchronous motor turns at 120 × f ÷ p rpm, where p is the number of poles, so a two-pole motor runs at 3,000 rpm on 50 Hz mains and 3,600 rpm on 60 Hz. Induction motors run a few percent below this synchronous speed, for example 2,900 rpm on 50 Hz.

### How do I convert Hz to rad/s?

Multiply by 2π, about 6.28319: ω = 2πf. 50 Hz is 314.16 rad/s and 1 Hz is 6.2832 rad/s. Both units reduce to “per second”, but a hertz counts whole cycles while a radian per second counts the angle swept, and one cycle is 2π radians.

### How many Hz is 120 BPM?

2 Hz: 120 beats ÷ 60 seconds. Tempo in beats per minute converts to hertz by dividing by 60, so 90 BPM is 1.5 Hz. The same rule applies to heart rate: the American Heart Association's normal adult resting range of 60 to 100 beats per minute is 1 to 1.67 Hz.

### How many MHz are in a GHz?

1,000. SI prefixes step by 1,000: 1 GHz = 1,000 MHz = 1,000,000 kHz = 10⁹ Hz. Wi-Fi's 2.4 GHz band is 2,400 MHz, and a 3.5 GHz processor clock ticks 3.5 billion times a second. Frequency prefixes are always decimal, never the binary 1,024 used for some memory sizes.

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

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 : 4. Par exemple, « 3000 rpm in Hz » est vérifié à l’aide de 3000 / 60 = 50.

### 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)