Frequency Converter

Convert Frequency Units Online — Hz, kHz, MHz, GHz, and RPM

Our free frequency converter lets you instantly switch between hertz, kilohertz, megahertz, gigahertz, revolutions per minute, and other frequency units. Whether you are tuning audio equipment, analyzing radio signals, checking CPU clock speeds, or calibrating motor rotation rates, this tool provides accurate results in real time. All calculations run directly in your browser with no data sent to any server and no registration required. Frequency measurement is fundamental across electronics, physics, music, and mechanical engineering, making a reliable frequency converter an essential everyday tool.

How to Convert Between Frequency Units

Frequency conversion follows a straightforward pattern of multiplying or dividing by powers of ten for metric prefixes, or applying specific ratios for non-metric units like RPM. Below are the key formulas and step-by-step examples for the most common conversions.

Hertz to Kilohertz (Hz to kHz)

The formula is kHz = Hz / 1,000. One kilohertz equals 1,000 hertz. To convert, simply divide the hertz value by 1,000. For example, 44,100 Hz (the standard audio CD sample rate) equals 44.1 kHz. In the reverse direction, multiply kilohertz by 1,000 to get hertz: 20 kHz equals 20,000 Hz, which is the upper limit of human hearing. Our hz to khz conversion handles any value with full decimal precision.

Megahertz to Gigahertz (MHz to GHz)

The formula is GHz = MHz / 1,000. One gigahertz equals 1,000 megahertz. For example, a CPU running at 3,500 MHz operates at 3.5 GHz. Wi-Fi networks commonly operate at 2,400 MHz (2.4 GHz) or 5,000 MHz (5 GHz). The newer Wi-Fi 6E standard extends into the 6 GHz band, which spans from 5,925 MHz to 7,125 MHz. You can explore specific conversions with our MHz to GHz converter.

RPM to Hertz

The formula is Hz = RPM / 60. Revolutions per minute measures rotational frequency, while hertz measures cycles per second. Dividing RPM by 60 converts from per-minute to per-second. For example, a motor spinning at 3,600 RPM rotates at 60 Hz, which matches the frequency of AC power in North America. A car engine idling at 750 RPM operates at 12.5 Hz. To convert back, multiply hertz by 60: 50 Hz equals 3,000 RPM, which corresponds to the AC power frequency used in Europe and most of Asia.

Kilohertz to Megahertz and General Metric Conversions

All metric frequency conversions follow the same pattern. 1 MHz = 1,000 kHz = 1,000,000 Hz, and 1 GHz = 1,000 MHz = 1,000,000 kHz = 1,000,000,000 Hz. To move up one prefix level, divide by 1,000. To move down, multiply by 1,000. For example, the AM radio band spans roughly 530 kHz to 1,700 kHz, which is 0.53 MHz to 1.7 MHz. FM radio operates from 87.5 MHz to 108 MHz, or 87,500 kHz to 108,000 kHz. These conversions are purely a matter of shifting the decimal point by three places per prefix step.

About the Frequency Converter

Frequency describes how often a repeating event occurs per unit of time. It is one of the most widely measured quantities in science and engineering, appearing in contexts from sound waves and light to electrical circuits and rotating machinery. This frequency converter supports all standard units including hertz, kilohertz, megahertz, gigahertz, terahertz, and revolutions per minute. If you also work with energy calculations related to electromagnetic frequency, our energy unit conversion tool can help with photon energy and wavelength relationships.

Understanding Frequency and Its Measurement

The hertz (Hz) is the SI unit of frequency, named after German physicist Heinrich Hertz, who first conclusively proved the existence of electromagnetic waves in 1887. One hertz means one cycle per second. Before the adoption of "hertz" in 1960 by the General Conference on Weights and Measures, frequency was expressed simply as "cycles per second" (cps). The unit honors Hertz's groundbreaking experiments at the University of Karlsruhe, where he generated and detected radio waves using spark-gap transmitters and receivers.

Frequency and period are inversely related: frequency = 1 / period. If a wave completes one cycle every 0.001 seconds (a period of 1 millisecond), its frequency is 1,000 Hz or 1 kHz. This reciprocal relationship is fundamental to understanding oscillations in any domain. In electronics, oscilloscopes display waveforms in the time domain, and engineers routinely convert between period and frequency to characterize signals.

Frequency also relates directly to wavelength for waves traveling at a known speed. The formula is wavelength = speed / frequency. For electromagnetic waves in a vacuum, the speed is approximately 299,792,458 meters per second. A 100 MHz FM radio signal has a wavelength of about 3 meters, while a 2.4 GHz Wi-Fi signal has a wavelength of roughly 12.5 centimeters. For sound waves in air at room temperature (approximately 343 meters per second), a 440 Hz tone (concert pitch A) has a wavelength of about 0.78 meters. These relationships are essential in antenna design, acoustics, and optical engineering.

Common Frequency Conversions in Daily Life

Audio production is one of the most frequent contexts for frequency conversion. The human ear can detect sounds from roughly 20 Hz to 20 kHz. Bass frequencies in music typically range from 60 Hz to 250 Hz, midrange from 250 Hz to 4 kHz, and treble from 4 kHz to 20 kHz. Audio engineers working with equalizers, synthesizers, and digital audio workstations constantly convert between Hz and kHz when setting filter cutoff points, resonance peaks, and sample rates. The standard CD sample rate of 44.1 kHz (44,100 Hz) was chosen to satisfy the Nyquist theorem for capturing frequencies up to 22.05 kHz.

Radio and telecommunications rely heavily on MHz and GHz conversions. AM radio stations broadcast between 530 kHz and 1,700 kHz. FM radio spans 87.5 MHz to 108 MHz. Cellular networks operate across multiple bands: 4G LTE uses frequencies from 700 MHz to 2,600 MHz, while 5G extends into millimeter wave bands at 24 GHz to 47 GHz. Satellite communications use the C-band (4 to 8 GHz), Ku-band (12 to 18 GHz), and Ka-band (26.5 to 40 GHz). Converting between these units helps engineers plan coverage, calculate antenna dimensions, and troubleshoot interference. For related velocity calculations, our speed unit conversion tool handles wave propagation speeds.

In computing, CPU clock speeds are expressed in GHz. A processor rated at 4.2 GHz executes 4,200,000,000 clock cycles per second. Overclocking enthusiasts push frequencies higher, sometimes reaching 5 GHz or beyond with advanced cooling. Memory modules (RAM) also have clock ratings — DDR5 memory operates at frequencies from 4,800 MHz to over 8,000 MHz. Understanding these frequencies helps when comparing hardware specifications, diagnosing performance bottlenecks, and ensuring component compatibility.

Mechanical engineering uses RPM extensively. Electric motors, engines, turbines, centrifuges, and power tools all specify rotational speed in RPM. A typical washing machine drum spins at 1,000 to 1,600 RPM during the spin cycle. Industrial centrifuges can reach 10,000 to 100,000 RPM. Converting RPM to hertz is necessary when analyzing vibration signatures, balancing rotating equipment, or matching motor speeds to power line frequency. In regions with 60 Hz power, synchronous motors naturally spin at multiples of 3,600 RPM, while 50 Hz regions see multiples of 3,000 RPM.

Tips and Quick Reference for Frequency

A handy shortcut for metric frequency conversions: each prefix step (Hz to kHz, kHz to MHz, MHz to GHz) moves the decimal point three places. So 2,400,000 Hz becomes 2,400 kHz, then 2.4 MHz, then 0.0024 GHz. Counting groups of three zeros is the fastest mental math approach for these conversions.

For RPM to Hz, remember that 60 RPM equals exactly 1 Hz. This makes 60 a convenient anchor point. If a motor runs at 1,800 RPM, divide by 60 to get 30 Hz. If you know the frequency in hertz and need RPM, multiply by 60. This relationship is especially useful when working with AC power systems, where the line frequency (50 or 60 Hz) directly determines synchronous motor speeds.

When working with audio frequencies, remember that doubling the frequency raises the pitch by one octave. Concert A is 440 Hz, so one octave higher is 880 Hz and one octave lower is 220 Hz. The lowest note on a standard piano is A0 at 27.5 Hz, and the highest is C8 at 4,186 Hz. Middle C (C4) is 261.63 Hz. These reference points help musicians and audio engineers quickly estimate frequency ranges without a calculator. For time-based calculations related to frequency periods, our time unit conversion tool can assist with converting between seconds, milliseconds, and microseconds.

Common Frequency Reference Values

The following table provides quick reference conversions for frequently encountered frequency values across audio, radio, computing, and mechanical applications.

Description	Hertz (Hz)	kHz	MHz	RPM
Infrasound threshold	20 Hz	0.02 kHz	—	1,200 RPM
AC power (Europe)	50 Hz	0.05 kHz	—	3,000 RPM
AC power (North America)	60 Hz	0.06 kHz	—	3,600 RPM
Concert pitch A4	440 Hz	0.44 kHz	—	26,400 RPM
Upper hearing limit	20,000 Hz	20 kHz	0.02 MHz	1,200,000 RPM
AM radio (mid-band)	1,000,000 Hz	1,000 kHz	1 MHz	—
FM radio (mid-band)	100,000,000 Hz	100,000 kHz	100 MHz	—
Wi-Fi 2.4 GHz band	2,400,000,000 Hz	2,400,000 kHz	2,400 MHz	—
Wi-Fi 5 GHz band	5,000,000,000 Hz	5,000,000 kHz	5,000 MHz	—
Modern CPU clock	4,000,000,000 Hz	4,000,000 kHz	4,000 MHz	—

Frequently Asked Questions

What is the difference between Hz and kHz?

Hertz (Hz) measures frequency in cycles per second, while kilohertz (kHz) equals 1,000 hertz. The kHz unit is simply a more convenient way to express larger frequency values. For example, the standard audio sample rate of 44,100 Hz is more commonly written as 44.1 kHz. The relationship is purely a matter of scale — 1 kHz is always exactly 1,000 Hz, with no rounding or approximation involved.

How do I convert RPM to Hz?

Divide the RPM value by 60. Since RPM measures revolutions per minute and Hz measures cycles per second, and there are 60 seconds in a minute, the conversion factor is simply 60. A motor running at 1,800 RPM operates at 30 Hz. Conversely, multiply Hz by 60 to get RPM: a 50 Hz signal corresponds to 3,000 RPM. This conversion is essential in mechanical engineering, vibration analysis, and power systems where rotational and electrical frequencies must be matched.

Why are internet speeds measured in MHz and GHz?

Wireless internet signals are electromagnetic waves that oscillate at specific frequencies. Wi-Fi routers transmit at 2.4 GHz or 5 GHz, meaning the radio waves oscillate 2.4 billion or 5 billion times per second. Higher frequencies can carry more data but have shorter range and poorer penetration through walls. The frequency band determines the channel width, available bandwidth, and interference characteristics. Wired internet speeds, by contrast, are measured in bits per second rather than frequency, though the underlying electrical signals also have characteristic frequencies.

What frequency is middle C on a piano?

Middle C (C4) has a frequency of 261.63 Hz in standard tuning where A4 equals 440 Hz. Each octave doubles the frequency, so C5 is 523.25 Hz and C3 is 130.81 Hz. The equal temperament tuning system divides each octave into 12 semitones, with each semitone representing a frequency ratio of the twelfth root of 2 (approximately 1.05946). This mathematical relationship means that frequency conversion is essential for music theory, instrument tuning, and digital audio synthesis.

What is the relationship between frequency and wavelength?

Frequency and wavelength are inversely proportional for any wave traveling at a constant speed. The formula is wavelength equals speed divided by frequency. For electromagnetic waves in a vacuum, the speed is about 299,792,458 meters per second. A 1 GHz signal has a wavelength of approximately 30 centimeters. A 100 MHz FM radio signal has a wavelength of about 3 meters. For sound in air at 20 degrees Celsius (speed approximately 343 m/s), a 1 kHz tone has a wavelength of about 34.3 centimeters. This relationship is critical for antenna design, room acoustics, and optical engineering.

How fast is a 5 GHz processor?

A 5 GHz processor executes 5 billion clock cycles per second. Each cycle, the processor can perform one or more operations depending on its architecture. Modern CPUs with superscalar designs and instruction-level parallelism can complete multiple instructions per cycle. However, clock speed alone does not determine overall performance — factors like core count, cache size, instructions per cycle (IPC), and memory bandwidth all play significant roles. A 4 GHz processor with higher IPC can outperform a 5 GHz processor with lower IPC. Still, within the same architecture, higher clock frequency directly translates to faster execution.

What is the Nyquist frequency and why does it matter?

The Nyquist frequency is half the sampling rate of a digital system. According to the Nyquist-Shannon sampling theorem, a digital system must sample at least twice the highest frequency present in a signal to accurately reproduce it. For CD audio sampled at 44.1 kHz, the Nyquist frequency is 22.05 kHz, which comfortably exceeds the 20 kHz upper limit of human hearing. Sampling below the Nyquist rate causes aliasing, where high-frequency components are misrepresented as lower frequencies, producing audible distortion. This principle applies to all digital signal processing, not just audio.

Why do different countries use 50 Hz or 60 Hz power?

The choice between 50 Hz and 60 Hz AC power is largely historical. Early electrical systems in Europe standardized on 50 Hz, while North America adopted 60 Hz. Nikola Tesla originally proposed 60 Hz as optimal for his polyphase AC system, and Westinghouse adopted this standard in the United States. German company AEG chose 50 Hz for its systems, and this spread across Europe and much of the rest of the world. The practical differences are minor: 60 Hz transformers can be slightly smaller and lighter, while 50 Hz systems experience marginally less energy loss in long-distance transmission. Both frequencies work well for lighting, motors, and household appliances, but equipment designed for one frequency may not function correctly on the other without modification.

What is resonant frequency?

Resonant frequency is the natural frequency at which a system oscillates with the greatest amplitude when driven by an external force. Every physical object and electrical circuit has one or more resonant frequencies determined by its physical properties. A guitar string vibrates at its resonant frequency when plucked. An LC circuit (inductor-capacitor) resonates at a frequency determined by the formula f = 1 / (2 * pi * sqrt(L * C)), where L is inductance and C is capacitance. Resonance is exploited in radio tuning, musical instruments, and microwave ovens, but it can also be destructive — the famous Tacoma Narrows Bridge collapse in 1940 was partly attributed to wind-induced resonance.

How do I measure frequency at home?

For audio frequencies, smartphone apps can act as basic spectrum analyzers, displaying the frequency content of sounds picked up by the microphone. For electrical signals, a digital multimeter with a frequency function can measure AC line frequency and simple waveforms. More advanced measurements require an oscilloscope, which displays waveforms in real time and can measure frequency, period, amplitude, and phase. Software-defined radio (SDR) dongles costing as little as 20 to 30 dollars can receive and analyze radio frequencies from about 25 MHz to 1.7 GHz, making them popular tools for hobbyists and students.

What frequencies are used in medical imaging?

Medical ultrasound typically operates between 1 MHz and 20 MHz. Lower frequencies (1 to 5 MHz) penetrate deeper into the body and are used for abdominal and cardiac imaging. Higher frequencies (7 to 20 MHz) provide better resolution but less penetration, making them suitable for superficial structures like tendons, blood vessels, and the thyroid. MRI machines use radiofrequency pulses in the range of 10 to 300 MHz, depending on the magnetic field strength. The Larmor frequency, which determines the RF pulse frequency, is proportional to the magnetic field — a 1.5 Tesla MRI operates at about 63.9 MHz, while a 3 Tesla system uses about 127.7 MHz.

Can I use this frequency converter offline?

Yes. All calculations run entirely in your browser using client-side JavaScript. Once the page has loaded, no internet connection is needed for conversions. No data is transmitted to any server during the process. This makes the tool ideal for engineers in the field, students in classrooms, musicians in studios, and anyone working in a location with limited connectivity. Bookmark this page for quick access whenever you need to convert between hertz, kilohertz, megahertz, gigahertz, RPM, and other frequency units.