Frequency Converter
Convert between hertz, kilohertz, megahertz, gigahertz, and RPM.
How frequency conversion works
Hertz measures cycles per second — one hertz is one complete cycle every second. RPM (revolutions per minute) measures the same underlying idea, rotations, but counted per minute instead of per second, which is why 1 Hz equals exactly 60 RPM.
The formulas are RPM = Hz × 60 and Hz = RPM ÷ 60. The metric prefixes scale by 1,000 each step: kilohertz, megahertz and gigahertz are 1,000, 1,000,000 and 1,000,000,000 hertz.
Worked example
A hard drive spins at 7,200 RPM. In hertz that is 7,200 ÷ 60 = 120 Hz. A Wi-Fi band quoted as 2.4 GHz is 2.4 × 1,000 = 2,400 MHz, or 2,400,000,000 Hz.
Common conversions
| Conversion | Result |
|---|---|
| 1 kHz in hertz | 1,000 Hz |
| 1 MHz in kilohertz | 1,000 kHz |
| 1 GHz in megahertz | 1,000 MHz |
| 98.1 MHz in hertz | 98,100,000 Hz |
| 50 Hz in RPM | 3,000 RPM |
| 60 Hz in RPM | 3,600 RPM |
| 1,000 RPM in hertz | 16.666667 Hz |
Reading the mains figures
Mains electricity is 60 Hz in the US and 50 Hz in most of the rest of the world. The two RPM rows above show what those frequencies mean as rotations per minute: a simple two-pole AC motor tends toward 3,000 RPM on 50 Hz and 3,600 RPM on 60 Hz. Real induction motors run a little slower than that ideal because of slip.
Frequently asked questions
Why does RPM matter for motors and engines?
RPM directly describes how fast a motor or engine's shaft is spinning, which is a more intuitive unit for mechanical equipment than hertz — car tachometers, drill speeds, and washing machine spin cycles are all specified in RPM rather than hertz for that reason.
What's the difference between MHz and GHz for electronics?
They're just different scales of the same unit — 1 GHz = 1,000 MHz. Modern CPU clock speeds are typically specified in GHz, while radio and older computer specifications more often use MHz.