The computer speed is measured in

Concept

The processing speed of a computer refers to how fast its CPU executes instructions. A CPU works in step with an internal clock, and the rate of that clock is a frequency — the number of cycles completed per second. Frequency is measured in hertz (Hz), where 1 Hz means one cycle per second.

Application

Because a faster clock means more cycles — and therefore more instructions — per second, computer (processor) speed is expressed as a clock frequency. Modern CPUs run at billions of cycles per second, so their speed is quoted in megahertz (MHz, millions of Hz) and gigahertz (GHz, billions of Hz). The unit of speed is therefore hertz.

Contrast

• Kilobyte and Megabyte are units of storage or data size (a count of bytes), not a rate over time, so they describe how much a computer can hold, not how fast it runs.

• "Bites" is not a real computing unit; the genuine data unit is the "bit" (a single 0 or 1), which still measures amount of data, not speed.

Cross-check

A quantity is a speed only if it has the form something-per-second. Cycles-per-second fits that form, while byte-based units carry no time dimension at all.