Frequency Units — Hz, kHz, MHz, GHz Explained
Frequency measures how often something repeats per second. From the 50 Hz power grid in your wall to the 3.5 GHz processor in your laptop — frequency is everywhere in technology and science.
The Frequency Scale
| Unit | Value | Common use |
|---|---|---|
| 1 Hz | 1 cycle/second | Power grid (50/60 Hz), sound bass |
| 1 kHz | 1,000 Hz | Audio range, AM radio starts here |
| 1 MHz | 1,000,000 Hz | AM radio, early CPUs |
| 1 GHz | 1,000,000,000 Hz | Modern CPUs, WiFi, 5G networks |
| 1 THz | 10¹² Hz | Terahertz imaging, infrared light |
Real-World Frequency Examples
- Human hearing: 20 Hz – 20,000 Hz (20 kHz)
- AM radio: 530 – 1,700 kHz
- FM radio: 88 – 108 MHz
- WiFi 2.4 GHz: 2,400 – 2,484 MHz
- WiFi 5 GHz: 5,150 – 5,850 MHz
- 5G networks: 600 MHz – 86 GHz
- Modern CPUs: 3–5 GHz
- Microwave oven: 2.45 GHz
RPM to Hz Conversion
RPM (Revolutions Per Minute) is a rotational frequency. To convert to Hz: divide by 60. A car engine idling at 750 RPM = 12.5 Hz. An electric motor at 3,600 RPM = 60 Hz.
🎵 Audio fact: Middle C on a piano is 261.63 Hz. Concert A (the tuning note) is exactly 440 Hz. Human speech is mostly 100–8,000 Hz.