What Is a Frequency Converter?
A frequency converter translates how often a repeating event occurs between units. The hertz is the SI unit, defined as one cycle per second. Radio signals are measured in megahertz and gigahertz. Computer processors run in gigahertz. Rotating machinery is rated in revolutions per minute (rpm). Angular frequency in physics uses radians per second. These all describe the same concept, cycles per unit time, but the units span 12 orders of magnitude, from the 60 Hz hum of a power grid to the 2.4 GHz signal of a Wi-Fi router.
You need frequency conversion when comparing a 3,600 rpm hard drive platter to its hertz equivalent, translating a 5 GHz Wi-Fi channel to megahertz for a regulatory table, or converting angular frequency from a differential equation into cycles per second. For the wavelength that corresponds to a given frequency, see our Wavelength Calculator.
What This Calculator Does
This converter handles seven frequency units: hertz, kilohertz, megahertz, gigahertz, terahertz, revolutions per minute, and radians per second. Enter a value, pick the source and target units, and the result appears instantly. A swap button reverses the direction, and a full table shows your input in every supported unit at once.
- Inputs: A numeric value, source unit, and target unit
- Outputs: Converted result, conversion details, and a table of all units
How the Conversion Works
The calculator first converts the input to hertz, the SI base unit, then divides by the target unit's hertz factor. One hertz is one cycle per second. The SI prefixes (kilo, mega, giga, tera) scale by powers of 1,000. Revolutions per minute convert by dividing by 60, since one minute is 60 seconds. Radians per second convert by dividing by 2 times pi, because one full cycle is 2 pi radians.
For example, converting 3,600 rpm to hertz: 3,600 divided by 60 equals 60 Hz. Converting 60 Hz to radians per second: 60 times 2 pi equals 376.99 rad/s. Converting 2.4 GHz to megahertz: 2.4 times 1,000 equals 2,400 MHz.
Common Conversion Factors
| Unit | In Hertz | Typical Use |
|---|---|---|
| 1 Hertz (Hz) | 1 | Power grid, audio, clocks |
| 1 Kilohertz (kHz) | 1,000 | AM radio, audio range |
| 1 Megahertz (MHz) | 1,000,000 | FM radio, older CPUs |
| 1 Gigahertz (GHz) | 1,000,000,000 | Wi-Fi, modern CPUs |
| 1 Terahertz (THz) | 1,000,000,000,000 | Infrared, spectroscopy |
| 1 rpm | 0.0166667 | Motors, engines, drives |
| 1 rad/s | 0.159155 | Physics, signal processing |
How to Use the Calculator
- Enter the frequency value you want to convert.
- Select the unit you are converting from.
- Select the unit you are converting to, or click swap to reverse the direction.
- Read the result and the full conversion table below it.
Example Calculations
Example 1: Hard Drive RPM to Hertz
A 7,200 rpm hard drive spins its platters at 7,200 revolutions per minute. The user wants the frequency in hertz to understand vibration characteristics.
- Convert: 7,200 / 60 = 120 Hz
- In rad/s: 120 times 2 pi = 753.98 rad/s
- Result: 120 Hz, which is the rotational frequency of the platter
Example 2: Wi-Fi Channel GHz to MHz
A 5 GHz Wi-Fi router operates on channel 36, which is centered at 5.180 GHz. The user needs this in megahertz for a regulatory compliance form.
- Convert: 5.180 times 1,000 = 5,180 MHz
- In hertz: 5,180,000,000 Hz = 5.18 billion cycles per second
- Wavelength: 300,000,000 / 5,180,000,000 = 0.0579 meters (about 5.8 cm)
Real-World Scenarios
Motor Speed Control with a VFD
Carlos, an industrial maintenance technician, is tuning a variable frequency drive (VFD) for a 4-pole induction motor. The motor's synchronous speed at 60 Hz is 1,800 rpm (120 times frequency divided by poles). He wants to run the motor at 1,200 rpm for a conveyor application. Using the converter, 1,200 rpm equals 20 Hz. He sets the VFD output to 20 Hz, knowing the actual shaft speed will be slightly below 1,200 rpm due to slip (typically 2 to 5%). He also confirms the angular frequency: 20 Hz times 2 pi equals 125.66 rad/s, which he needs for a torque calculation in the control system. For the power draw of the motor, he references our Power Converter.
Audio Sample Rate and Pitch
Maya, a music producer, is working with a 44.1 kHz audio sample rate (CD quality). She reads that human hearing extends to about 20 kHz, and she wants to understand the relationship. Using the converter, 44.1 kHz equals 44,100 Hz, which is the number of amplitude samples per second. The Nyquist theorem says the maximum reproducible frequency is half the sample rate, so 44.1 kHz captures up to 22.05 kHz, which covers the full human hearing range. She also converts a low E string on a bass guitar, tuned to 41.2 Hz, to rpm for a visual effect in a music video: 41.2 times 60 equals 2,472 rpm. For timing her audio segments, she uses our Time Duration Calculator.
CPU Clock Speed Comparison
Daniel, a PC builder, is comparing two processors. One has a base clock of 3.8 GHz, the other 4.6 GHz. He wants to express the difference in hertz and in cycles per nanosecond to understand instruction latency. Using the converter, 3.8 GHz equals 3,800,000,000 Hz, and 4.6 GHz equals 4,600,000,000 Hz. The faster CPU completes one cycle every 0.217 nanoseconds (1 / 4.6), versus 0.263 nanoseconds for the slower one. A memory access that takes 10 cycles costs 2.17 ns on the faster chip versus 2.63 ns on the slower one. He notes that clock speed is only one factor in real performance, since instructions per cycle (IPC) and cache architecture matter just as much. For data transfer rates related to the CPU bus, he checks our Bandwidth Calculator.
Common Mistakes to Avoid
- Confusing frequency and angular frequency: Frequency in hertz counts cycles per second. Angular frequency in radians per second counts radians per second. One cycle is 2 pi radians, so 1 Hz equals 2 pi rad/s (about 6.283 rad/s). Mixing them up in physics equations introduces a factor of 2 pi error, which is about 6.28 times off.
- Forgetting rpm is per minute, not per second: 3,600 rpm is 60 Hz, not 3,600 Hz. The rpm to hertz conversion divides by 60. Engine tachometers, hard drive specs, and motor nameplates all use rpm, but physics and signal calculations use hertz. Always convert before plugging into formulas that expect hertz.
- Mixing up frequency and period: Frequency is cycles per second. Period is seconds per cycle. They are reciprocals: period = 1 / frequency. A 60 Hz signal has a period of 0.0167 seconds (16.7 ms). A 2.4 GHz signal has a period of 0.417 nanoseconds. Do not divide when you should multiply.
- Confusing clock speed with data rate: A 3.6 GHz CPU clock is not a 3.6 Gbps data rate. CPU clock speed measures internal cycle frequency. Data transfer rate depends on bus width, encoding, and multiplier. A 3.6 GHz CPU with a 64-bit memory bus transfers 64 bits per clock, but real throughput is lower due to overhead and latency.
Authoritative Research and Resources
- NIST Metric SI Prefixes - The National Institute of Standards and Technology defines the hertz as the SI unit of frequency and the kilo, mega, giga, and tera prefixes that scale it, providing the authoritative basis for frequency unit conversion.
- International Telecommunication Union (ITU) - The UN agency that allocates radio frequency bands worldwide, defining the frequency ranges used by AM and FM radio, television, cellular networks, Wi-Fi, and satellite communications in hertz, kilohertz, megahertz, and gigahertz.