Reference table
Frequency: hertz, kilohertz, megahertz and rpm
Hertz states cycles per second. Rotational speed is often given in revolutions per minute instead; the relation is fixed: 1 Hz = 60 rpm. The table spans mains frequency up to a CPU clock.
| Hz | kHz | MHz | rpm |
|---|---|---|---|
| 50 | 0.05 kHz | 0.00005 MHz | 3,000 rpm |
| 60 | 0.06 kHz | 0.00006 MHz | 3,600 rpm |
| 100 | 0.1 kHz | 0.0001 MHz | 6,000 rpm |
| 1,000 | 1 kHz | 0.001 MHz | 60,000 rpm |
| 1,000,000 | 1,000 kHz | 1 MHz | 60,000,000 rpm |
| 1,000,000,000 | 1,000,000 kHz | 1,000 MHz | 60,000,000,000 rpm |
| 2,400,000,000 | 2,400,000 kHz | 2,400 MHz | 144,000,000,000 rpm |
| 5,000,000,000 | 5,000,000 kHz | 5,000 MHz | 300,000,000,000 rpm |
Mains frequency is 50 Hz in Europe and 60 Hz in North America, which is why some electric motors and mains-driven clocks do not work in both regions without modification. The last two rows stand for WiFi and CPU clocks: 2.4 GHz and 5 GHz are the two WiFi bands, that is 2400 and 5000 MHz. Hertz and rpm describe physically the same thing; only the counting differs — 50 Hz is 3000 revolutions per minute.