How to Read CPU Clock Speed: MHz, GHz and What the Number Means
CPU specifications often lead with a number such as 3.6 GHz or 4.8 GHz. That number is useful, but only when you know what it measures and what it leaves out. This guide shows how to read the unit, convert it, and compare processor specifications without treating clock speed as a complete performance score.
2 min readPublished September 15, 2026Updated September 15, 2026
Hz, kHz, MHz and GHz
Hertz means cycles per second. A kilohertz is 1,000 Hz, a megahertz is 1,000,000 Hz, and a gigahertz is 1,000,000,000 Hz. Each step changes by a factor of 1,000.
1 GHz = 1,000 MHz = 1,000,000,000 Hz
The prefixes are decimal SI prefixes, so the factors are exact.
- 3.6 GHz = 3,600 MHz
- 4,800 MHz = 4.8 GHz
- A 5 GHz label is a frequency, not a promise of five times the performance.
Base clock and boost clock
Base clock is the guaranteed reference frequency under defined power and cooling conditions. Boost clock is a higher, opportunistic frequency that a processor may reach when temperature, power and workload allow it. A short boost peak is not the same as running every core at that speed all day.
| Specification | What it tells you |
|---|---|
| Base clock | A sustained reference point for supported conditions |
| Boost clock | A maximum target reached by some cores or workloads |
| Effective frequency | The frequency actually maintained during a specific workload |
Why GHz is not the whole story
Two CPUs at 4.0 GHz can complete different amounts of work per cycle. Architecture and IPC (instructions per cycle) affect single-thread speed, while core count and thread scheduling affect parallel workloads. Memory latency, cache size, power limits and cooling also influence the result.
- Compare CPUs from the same generation before using clock speed as a shortcut.
- Check whether the quoted number is single-core boost or an all-core sustained result.
- Use independent benchmarks for the software you actually run.
- Do not confuse CPU frequency with storage capacity or internet speed.
Quick answer
Frequently asked questions
How many MHz is 3.6 GHz?
Multiply by 1,000: 3.6 GHz equals 3,600 MHz.
Is a higher GHz CPU always faster?
No. A newer architecture can do more work per cycle, and workload, core count, cache, power limits and cooling all matter.
What is the difference between base and boost clock?
Base clock is the reference frequency under defined conditions. Boost clock is a higher short-term or workload-dependent target that may apply to one or more cores.