Hertz to Kilohertz Converter
Quickly convert from Hertz to Kilohertz.
How to convert
Formula:
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The number of repetitions of a periodic phenomenon per unit of time. The base unit is Hertz (1 cycle per second).
Where is it used?
In radio waves (MHz), in computer processors (GHz), and in music.
Examples:
• Electric current in Europe has a frequency of 50 Hz.
• A modern processor runs at 3-5 GHz.
• FM stations transmit around 88-108 MHz.
Frequency conversion connects the world of sound, radio, clocks, and quantum physics. Hertz, RPM, and radians per second all measure how often something repeats — from a heart beating at 1.2 Hz to a Wi-Fi signal oscillating at 2.4 GHz.
Frequency is the number of occurrences of a repeating event per unit of time. The SI unit is the hertz (Hz), equal to one cycle per second. Kilohertz (kHz) = 1,000 Hz; megahertz (MHz) = 10⁶ Hz; gigahertz (GHz) = 10⁹ Hz. Angular frequency (ω) in radians per second relates to frequency by ω = 2πf.
Where is it used?
- Audio & Music — Human hearing spans 20 Hz to 20,000 Hz. Concert A = 440 Hz. Bass frequencies: 20-300 Hz; treble: 2,000-20,000 Hz.
- Radio & Wireless — AM radio: 535-1,605 kHz; FM radio: 87.5-108 MHz; Wi-Fi: 2.4 GHz and 5 GHz; 5G: up to 100 GHz.
- Computing — CPU clock speeds in GHz (3-5 GHz for modern processors); RAM frequency in MHz.
- Engineering & Motors — AC power at 50 Hz (Europe/Asia) or 60 Hz (Americas); motor RPM converted to Hz.
- Medicine — Ultrasound at 1-18 MHz; ECG measures heart rate in Hz (bpm ÷ 60).
Common Conversion Mistakes
Confusing frequency with period
Frequency (Hz) = how many cycles per second. Period (s) = how long one cycle takes. They are reciprocals: f = 1/T. A 50 Hz power supply has a period of 0.02 seconds (20 milliseconds).
Mixing up angular frequency and regular frequency
ω (rad/s) = 2πf (Hz). A 60 Hz signal has ω = 2π × 60 ≈ 377 rad/s. Electrical engineering equations often use ω, while audio engineers use Hz — plugging one into the other's formula without conversion causes errors.
Assuming RPM and Hz are interchangeable
RPM (revolutions per minute) ÷ 60 = Hz (revolutions per second). A 3,000 RPM motor runs at 50 Hz. Remember to divide by 60 when converting.
Ignoring Nyquist limit in digital audio
To capture a frequency accurately, you need a sample rate at least twice as high (Nyquist theorem). CD audio at 44,100 Hz captures frequencies up to 22,050 Hz — just above the limit of human hearing.
Quick Reference Table
| From | To |
|---|---|
| 1 kHz | 1,000 Hz |
| 1 MHz | 1,000,000 Hz |
| 1 GHz | 10⁹ Hz |
| 1 Hz | 60 RPM |
| 3,000 RPM | 50 Hz |
| 440 Hz (Concert A) | ω ≈ 2,765 rad/s |
| 2.4 GHz (Wi-Fi) | 2,400,000,000 Hz |
| 50 Hz (EU power) | Period = 20 ms |
Frequently Asked Questions
What is the difference between Hz and RPM?
Both measure rotational or cyclic frequency. Hz = cycles per second. RPM = cycles per minute. To convert: Hz = RPM / 60. A hard drive spinning at 7,200 RPM = 120 Hz. Electric motors in 50 Hz countries often run at 3,000 RPM (synchronous speed = 60 × frequency).
How does frequency relate to musical pitch?
Musical pitch is determined by frequency. Each octave doubles the frequency: Middle C = 261.6 Hz, the C above = 523.2 Hz. Concert A = 440 Hz. The equal temperament scale divides each octave into 12 semitones, each a factor of 2^(1/12) ≈ 1.0595 apart.
What frequencies can humans hear?
Healthy young adults hear from about 20 Hz (very low bass) to 20,000 Hz (very high treble). With age, the upper limit decreases — most adults over 50 can only hear up to about 12,000-14,000 Hz. Ultrasound (>20 kHz) is used in medical imaging and cleaning.
Why is mains power 50 Hz or 60 Hz?
These frequencies were chosen in the late 1800s as a compromise between motor efficiency and flicker-free lighting. Europe standardized at 50 Hz; North America at 60 Hz. 60 Hz is slightly better for motors; 50 Hz requires less insulation. Neither is technically superior — it was historical accident.
Sources & Standards
- International Bureau of Weights and Measures (BIPM)
- Institute of Electrical and Electronics Engineers (IEEE)
- International Telecommunication Union (ITU)
Reviewed by The Unit Hub Editorial Team · March 2026