Converter

Frequency Converter

Convert between Hz, kHz, MHz, GHz, RPM, BPM, and rad/s. Shows period with presets for radio, music, and CPU speeds.

Quick Answer

440 Hz (concert A) = 0.44 kHz = 26,400 RPM = 2764.6 rad/s. Period = 2.273 ms. Use our converter for any frequency.

Period (1/f)
2.273 ms
Hz
440.000
kHz
0.440000
MHz
4.4000e-4
GHz
4.4000e-7
RPM
26400.0
BPM
26400.0
rad/s
2764.60

About This Tool

The Frequency Converter is a comprehensive tool for engineers, musicians, radio enthusiasts, and anyone working with periodic phenomena. It converts between seven frequency units (Hz, kHz, MHz, GHz, RPM, BPM, and rad/s), displays the corresponding period, and includes presets for common real-world frequencies spanning radio broadcasting, musical notes, computer hardware, and biological rhythms.

Understanding Frequency

Frequency measures how often a repeating event occurs per unit of time. The SI unit is the Hertz (Hz), defined as one cycle per second, named after Heinrich Hertz who first proved the existence of electromagnetic waves in 1887. Frequency is one of the most fundamental measurements in science and engineering, describing everything from the vibration of a guitar string to the oscillation of electromagnetic waves carrying your Wi-Fi signal. The human ear can detect frequencies from roughly 20 Hz (a deep rumble) to 20,000 Hz (a high-pitched whine), while electromagnetic frequencies used in daily technology span from 50/60 Hz (mains power) to several GHz (wireless communications).

SI Prefixes: kHz, MHz, GHz

The metric prefix system provides convenient shorthand for large frequencies. One kilohertz (kHz) equals 1,000 Hz and covers audio frequencies and AM radio. One megahertz (MHz) equals 1,000,000 Hz and spans FM radio, TV broadcasting, and older computer processors. One gigahertz (GHz) equals 1,000,000,000 Hz and covers modern CPU clock speeds, Wi-Fi, cellular networks, and microwave frequencies. Beyond GHz, terahertz (THz) radiation occupies the gap between microwaves and infrared light, used in security scanning and spectroscopy. Our converter covers the most practically useful range from sub-Hertz to gigahertz.

RPM, BPM, and Rotational Frequency

Revolutions per minute (RPM) and beats per minute (BPM) are both measures of frequency expressed in events per minute rather than per second. RPM is ubiquitous in mechanical engineering: car engines idle at 600-1000 RPM, spin at 2000-4000 RPM during normal driving, and may redline at 6000-9000 RPM. Hard drives spin at 5400 or 7200 RPM. Electric motors range from a few hundred RPM to over 100,000 RPM for dental drills. BPM is used in music (tempo) and medicine (heart rate). A resting heart beats at 60-100 BPM, while music tempos range from 40 BPM (grave) to over 200 BPM (prestissimo). Converting to Hz is simple: divide by 60.

Period: The Reciprocal of Frequency

Every frequency has a corresponding period, which is the duration of one complete cycle. Period equals 1 divided by frequency. This reciprocal relationship is fundamental to understanding waveforms and timing. A 60 Hz mains power signal has a period of 16.67 milliseconds. A 440 Hz concert A note has a period of 2.273 milliseconds. A 2.4 GHz Wi-Fi signal oscillates with a period of just 0.417 nanoseconds. Our tool displays the period in the most readable unit automatically, from hours (for very low frequencies) down to picoseconds (for GHz-range signals). This is particularly useful in electronics when you need to relate clock frequencies to timing constraints.

Frequency in Music

Music is fundamentally built on frequency relationships. The Western equal temperament system divides each octave (a 2:1 frequency ratio) into 12 equal semitones, each a ratio of 2^(1/12) apart. Concert pitch standardizes A4 at 440 Hz. From there, every note has a precise frequency: middle C (C4) is 261.63 Hz, E4 is 329.63 Hz, and G4 is 392.00 Hz. Musical intervals correspond to frequency ratios: an octave is 2:1, a perfect fifth is approximately 3:2, and a perfect fourth is approximately 4:3. The lowest note on a piano (A0) vibrates at 27.5 Hz, near the lower limit of human hearing, while the highest (C8) reaches 4186 Hz. Our presets include A4 and C4 as common reference points.

Angular Frequency (rad/s)

Angular frequency, measured in radians per second (rad/s), equals 2*pi times the ordinary frequency in Hz. While it may seem redundant, angular frequency simplifies many physics and engineering equations. In AC circuit analysis, impedance formulas use omega (angular frequency) directly. In mechanical vibration analysis, natural frequency is often expressed in rad/s. The angular frequency of a simple pendulum is sqrt(g/L) rad/s, where g is gravitational acceleration and L is pendulum length. When you see omega in physics textbooks, it almost always refers to angular frequency in rad/s. Our converter includes rad/s alongside the more commonly encountered units to serve physics and engineering applications.

Frequently Asked Questions

How do I convert Hz to RPM?
To convert Hertz to RPM (revolutions per minute), multiply by 60. One Hertz equals one cycle per second, and there are 60 seconds in a minute, so 1 Hz = 60 RPM. For example, an engine spinning at 3000 RPM operates at 50 Hz. This conversion is essential in mechanical engineering when relating rotational speed (typically expressed in RPM for motors, engines, and turbines) to electrical frequency (used for AC power and vibration analysis). Our converter handles this and all other frequency conversions bidirectionally.
What is the relationship between frequency and period?
Frequency and period are reciprocals: period = 1/frequency. If a signal oscillates at 1000 Hz (1 kHz), its period is 1/1000 second = 1 millisecond. Our tool automatically calculates and displays the period for any frequency you enter, using the most appropriate time unit (hours, minutes, seconds, milliseconds, microseconds, nanoseconds, or picoseconds). This relationship is fundamental in electronics, signal processing, and physics. Higher frequency means shorter period and vice versa. A 2.4 GHz Wi-Fi signal has a period of about 0.417 nanoseconds.
What are common radio frequencies?
Radio frequencies span an enormous range. AM radio broadcasts on 540-1700 kHz (medium wave). FM radio uses 88-108 MHz. VHF TV channels span 54-216 MHz, and UHF TV uses 470-890 MHz. Cell phones use various bands: 700 MHz, 850 MHz, 1900 MHz, and 2100 MHz for 4G LTE; 600 MHz, 2.5 GHz, 3.5 GHz, and 24-39 GHz for 5G. Wi-Fi operates at 2.4 GHz and 5 GHz (with Wi-Fi 6E adding 6 GHz). Bluetooth uses 2.4 GHz. GPS operates at 1.575 GHz (L1) and 1.227 GHz (L2). Microwave ovens use 2.45 GHz.
What frequency is concert pitch A?
Concert pitch A (A4, the A above middle C) is standardized at 440 Hz. This has been the international standard since 1955 (ISO 16), though some orchestras tune slightly higher (441-443 Hz) for a brighter sound. Historically, pitch varied widely: Baroque pitch was around 415 Hz, and some historical tunings used 432 Hz. Each octave doubles the frequency, so A3 is 220 Hz, A5 is 880 Hz, and A2 is 110 Hz. The equal temperament tuning system spaces all 12 semitones equally on a logarithmic scale, with each semitone being a frequency ratio of 2^(1/12), approximately 1.05946.
How is frequency related to musical notes?
In the equal temperament system used in Western music, each of the 12 semitones within an octave represents a frequency ratio of 2^(1/12). Starting from A4 = 440 Hz: A#4/Bb4 = 466.16 Hz, B4 = 493.88 Hz, C5 = 523.25 Hz, and so on. Going down: G#4/Ab4 = 415.30 Hz, G4 = 392.00 Hz, F#4/Gb4 = 369.99 Hz. Middle C (C4) is 261.63 Hz. The lowest note on a standard piano (A0) is 27.5 Hz, and the highest (C8) is 4186 Hz. Human hearing ranges from approximately 20 Hz to 20,000 Hz, encompassing more than the full piano range.
What is rad/s and how does it relate to Hz?
Radians per second (rad/s) is the angular frequency, also called angular velocity. It relates to Hz by the formula: angular frequency = 2*pi*frequency. So 1 Hz = 2*pi rad/s (approximately 6.2832 rad/s). Angular frequency is preferred in physics and electrical engineering because it simplifies many formulas. For example, the impedance of a capacitor is 1/(omega*C) where omega is in rad/s, and the resonant frequency of an LC circuit is 1/sqrt(LC) in rad/s. When you see omega (the Greek letter) in physics equations, it typically refers to angular frequency in rad/s rather than ordinary frequency in Hz.

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