Hertz: One cycle per second


Hertz abbreviated Hz, is a unit of frequency. One Hz means one cycle per second. Hz is named after the German physicist Heinrich Hertz who made considerable contributions to electromagnetism.


In computers, the CPU (central processing unit) and other components such as RAM are measured in Hz or MHz (Megahertz) and now GHz (Gigahertz).

One KHz equals 1,000 (one thousand) Hz, while 1,000,000 (one million) Hz equals one MHz, and 1,000,000,000 (one billion) Hz equals one GHz. Hopefully the table below will make it easier to understand.

Hertz1 Hz0.001 kHz0.000001 MHz
Kilohertz1,000 Hz1 kHz     0.001 MHz
Megahertz1,000,000 Hz1,000 kHz1 MHz
Gigahertz1,000,000,000 Hz1,000,000 kHz 1,000 MHz

For a CPU the MHz refers to the clock speed of the processor. This means that a number of bits (either 8, 16, 32, or 64) are manipulated at one million cycles per second. Sound fast?

Well that was a 1MHz CPU, (very,very slow). Now a days a 3GHz CPU is common and that means that a certain number of bits are being manipulated at 3 billion cycles per second. Now thats fast!

Common examples of megahertz are: A Pentium II CPU (300 MHz), running at 300,000,000 Hz.Or a 256MB RAM stick running at 166,000,000 Hz.

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