Convert Frequency Units
Frequency Converter
Frequency Conversion Chart
Key relationships between frequency units. The SI unit is the hertz (Hz), defined as one cycle per second.
SI Prefixes
| 1 kHz | = | 1,000 Hz | exact |
| 1 MHz | = | 1,000,000 Hz | exact |
| 1 GHz | = | 1,000,000,000 Hz | exact |
| 1 THz | = | 10¹² Hz | exact |
Rotational & Angular
| 1 RPM | = | 1/60 Hz | exact |
| 60 RPM | = | 1 Hz | exact |
| 1 Hz | = | 2π rad/s | exact |
| 1 rad/s | = | 1/(2π) Hz ≈ 0.15915 Hz | |
| 1 RPM | = | π/30 rad/s | exact |
Reference Frequencies
| Concert A (A4) | = | 440 Hz | ISO 16 (1975) |
| Mains power (US) | = | 60 Hz | exact |
| Mains power (EU) | = | 50 Hz | exact |
| WiFi 2.4 GHz | = | 2,400 MHz | |
| FM radio range | = | 87.5–108 MHz |
All SI prefix conversions are exact powers of 10. The relationship 1 Hz = 2π rad/s is exact by mathematical definition. Heinrich Hertz demonstrated electromagnetic waves in 1887; the unit was named in his honor in 1930.
About Frequency Units
Radio, WiFi & Telecom
Radio stations broadcast in MHz (FM: 87.5–108 MHz, AM: 535–1705 kHz). WiFi operates at 2.4 GHz and 5 GHz. 5G networks use frequencies up to 39 GHz (mmWave). Higher frequency = more bandwidth but shorter range.
Audio & Music
Human hearing ranges from 20 Hz to 20 kHz. The standard tuning pitch A4 = 440 Hz (ISO 16). Audio sampling: CD quality uses 44.1 kHz (44,100 samples per second), based on the Nyquist theorem.
Mechanical & Motors
Engine and motor speeds are measured in RPM (revolutions per minute). A typical car engine idles at 600–1000 RPM. Hard drives spin at 5,400 or 7,200 RPM. To convert: divide RPM by 60 to get Hz.
Frequency measures how many times an event repeats per second. 1 Hz = 1 cycle/second. The hertz applies to any periodic event — electromagnetic waves, sound waves, mechanical vibrations, or processor clock cycles.
Popular Frequency Conversions
Frequently Asked Questions
What is the difference between Hz, kHz, MHz, and GHz?
They are all units of frequency differing by factors of 1,000. 1 kHz = 1,000 Hz, 1 MHz = 1,000,000 Hz, 1 GHz = 1,000,000,000 Hz. Hertz (Hz) measures cycles per second — the higher the number, the faster the oscillation. Radio stations broadcast in MHz, WiFi operates at 2.4 and 5 GHz, and processors run in the GHz range.
How do I convert RPM to Hz?
Divide RPM by 60. Since RPM counts revolutions per minute and Hz counts cycles per second, you simply divide by 60 to convert minutes to seconds. For example, a motor running at 3,600 RPM equals 60 Hz — which is the US mains power frequency.
Why do some countries use 50 Hz and others 60 Hz for mains power?
Historical engineering decisions. The US adopted 60 Hz (largely influenced by Nikola Tesla and Westinghouse), while Europe standardized on 50 Hz. The 50 Hz system is slightly more efficient for long-distance transmission, while 60 Hz allows slightly smaller transformers. Modern equipment is typically designed to work with both frequencies.
What is the concert pitch frequency?
The international standard for concert pitch is A4 = 440 Hz, established by ISO 16 in 1975. This means the A note above middle C vibrates at 440 cycles per second. Some orchestras tune slightly higher (441–443 Hz) for a brighter sound.
Related Converter Categories
- Time Converter — Frequency = 1 ÷ period
- Angle Converter — Angular frequency: 1 Hz = 2π rad/s
- Power Converter — Motor power at given RPM
