时钟频率（又译：时脉速度，英语：clock rate）是指同步电路中时钟的基础频率，它以“每秒时钟周期”（clock cycles per second）来度量，量度单位采用SI单位赫兹（Hz）。例如，来自晶振的基准频率通常等于一个固定的正弦波形，则时钟频率就是这个基准频率，电子电路会为数字电子设备将它转化成对应的脉冲方波。需要补充一点的是，“速度”作为矢量不应与标量“频率”相混淆，所以使用“时钟速度”来描述这个概念是用词不当的。

在单个时钟 周期内（现代非嵌入式微处理器的这个时间一般都短于一纳秒）逻辑零状态与逻辑一状态来回切换。 由于发热和电气规格的限制， 周期里逻辑零状态的持续时间历来要长于逻辑一状态。

The clock rate typically refers to the frequency at which a chip like a central processing unit (CPU), one core of a multi-core processor, is running and is used as an indicator of the processor's speed. It is measured in clock cycles per second or its equivalent, the SI unit hertz (Hz). The clock rate of the first generation of computers was measured in hertz or kilohertz (kHz), but in the 21st century the speed of modern CPUs is commonly advertised in GigaHertz (GHz). This metric is most useful when comparing processors within the same family, holding constant other features that may impact performance. Video card and CPU manufacturers commonly select their highest performing units from a manufacturing batch and set their maximum clock rate higher, fetching a higher price.