Hertz, Kilohertz, and GHz: Understanding Frequency Units

Frequency measures how often something repeats per second. It appears everywhere in modern life — from the processor speed of your computer to the radio stations you listen to, from musical notes to WiFi signals.

What is Frequency?

Frequency is measured in Hertz (Hz), where 1 Hz means one cycle per second. The unit is named after Heinrich Hertz, who first proved the existence of electromagnetic waves.

Frequency Scale

• 1 Hz = 1 cycle per second
• 1 kHz (kilohertz) = 1,000 Hz
• 1 MHz (megahertz) = 1,000,000 Hz
• 1 GHz (gigahertz) = 1,000,000,000 Hz
• 1 THz (terahertz) = 1,000,000,000,000 Hz

Everyday Frequency Examples

Music and Sound

• Human hearing range: 20 Hz to 20,000 Hz (20 kHz)
• Middle C on piano: 261.6 Hz
• Concert A (tuning standard): 440 Hz
• Bass guitar lowest note: ~41 Hz

Radio and Communication

• AM radio: 530 kHz - 1,700 kHz
• FM radio: 87.5 MHz - 108 MHz
• WiFi 2.4 GHz band: 2,400 MHz
• WiFi 5 GHz band: 5,000 MHz
• 5G cellular: 600 MHz - 39 GHz

Computing

• Modern CPU clock speed: 3-5 GHz
• RAM frequency: 3,200 MHz - 7,200 MHz
• USB data transfer rates are also measured in MHz/GHz

Power Systems

• US electrical grid: 60 Hz
• European electrical grid: 50 Hz
• This is why some electronics need adapters when traveling internationally — it is not just about voltage, but frequency too.