Frequency Units Guide
From Hz to GHz — understand sound, radio, WiFi, and CPU frequencies
Overview
Frequency measures how often something occurs per unit of time. The SI unit is the hertz (Hz), representing one cycle per second. Frequency is essential in sound, radio, computing, and physics.
Higher frequency means more cycles per second — from the low hum of power lines (50-60 Hz) to WiFi signals (billions of Hz).
Common Frequency Units
Hertz
1 cycle/second
SI base unit
Kilohertz
1,000 Hz
Audio, AM radio
Megahertz
1,000,000 Hz
FM radio, CPU
Gigahertz
1,000,000,000 Hz
WiFi, processors
Frequency Unit Comparison
| Unit | In Hertz | Scientific Notation | Common Use |
|---|---|---|---|
| Hertz (Hz) | 1 | 100 | Audio frequencies, AC power |
| Kilohertz (kHz) | 1,000 | 103 | AM radio, audio sampling |
| Megahertz (MHz) | 1,000,000 | 106 | FM radio, old processors |
| Gigahertz (GHz) | 1,000,000,000 | 109 | WiFi, modern CPUs |
| Terahertz (THz) | 1,000,000,000,000 | 1012 | Imaging, spectroscopy |
Sound Frequencies
Human Hearing Range
Humans can hear frequencies from approximately 20 Hz to 20,000 Hz (20 kHz).
- 20-200 Hz: Bass (subwoofer range)
- 200-2,000 Hz: Midrange (voice, instruments)
- 2,000-20,000 Hz: Treble (cymbals, high notes)
Musical Notes
- A4 (concert pitch): 440 Hz
- Middle C (C4): 261.63 Hz
- Low E (bass guitar): 41.2 Hz
- High C (soprano): 1,046.5 Hz
Each octave doubles the frequency.
Real-World Frequency Examples
Frequency and Wavelength
The Relationship
Frequency and wavelength are inversely related:
Wavelength = Speed / Frequency
For electromagnetic waves (light, radio):
λ = c / f
Where c = speed of light (3 × 108 m/s)
Examples
- FM Radio (100 MHz): 3 m wavelength
- WiFi (2.4 GHz): 12.5 cm wavelength
- Red light (430 THz): 700 nm wavelength
- Blue light (670 THz): 450 nm wavelength
Quick Conversion Tips
Divide by 1,000
44,100 Hz = 44.1 kHz
Divide by 1,000
2,400 MHz = 2.4 GHz
Period (T) = 1 / Frequency (f)
60 Hz → T = 16.7 ms
kilo = 103
mega = 106
giga = 109