Frequency Converter: Hz, kHz, MHz, GHz & RPM
Convert between hertz, kilohertz, megahertz, gigahertz, terahertz, and rotational speed units like RPM and radians per second, instantly in your browser.
How the frequency converter links Hertz to RPM and radians per second
Frequency is simply how many times something repeats per second, but the unit you reach for depends entirely on what is repeating. Electrical engineers say Hertz. Mechanics say revolutions per minute. Physicists working with rotating systems say radians per second. All three describe the same underlying idea, a cycle count over time, and this tool treats Hertz as the anchor unit since it is the SI derived unit for frequency, then converts every rotational unit through it.
All math runs locally in the browser using a static object of multiplicative factors. Nothing is sent anywhere, so a frequency value you’re testing for, say, audio engineering work stays private by default.
The conversion logic, including how RPM gets folded in
1/60, because 1 revolution per minute equals one sixtieth of a revolution per second, which is the definition of one sixtieth of a Hertz for rotational counting.
1/(2π), which is the same as multiplying by 2π, reflecting that one full cycle equals 2π radians.
Full unit table, factor relative to one hertz
| Unit | Symbol | Factor (Hz) |
|---|---|---|
| Hertz | Hz | 1 (base unit) |
| Kilohertz | kHz | 1,000 |
| Megahertz | MHz | 1,000,000 |
| Gigahertz | GHz | 1,000,000,000 |
| Terahertz | THz | 1,000,000,000,000 |
| Revolutions per minute | RPM | 0.016667 (1/60) |
| Revolutions per second | RPS | 1 |
| Radians per second | rad/s | 0.159155 (1/2π) |
Two contexts where this table gets used daily
Audio and electronics
Concert pitch A above middle C is standardized at 440 Hz, the tool’s default example. Radio bands, processor clock speeds in GHz, and AC mains frequency at 50 or 60 Hz all live in the Hz through THz range of this table.
Mechanical and motor engineering
Motor nameplates and tachometers report RPM almost exclusively, while control system equations for angular velocity are written in radians per second, making the RPM to rad/s conversion one of the most common lookups in motion control work.
Standards behind the unit
The Hertz was adopted internationally in 1960 as part of the SI, named for Heinrich Hertz, who proved the existence of electromagnetic waves in 1887. It is formally a reciprocal second, one cycle per second, which makes it dimensionally simple but conceptually broad: it applies equally to a vibrating string, an AC power grid, and a spinning turbine, which is exactly why a converter needs both the pure frequency units and the rotational ones side by side.
Frequency references
- BIPM SI Brochure defines Hertz as the SI coherent derived unit for frequency.
- NIST Units and Systems of Measurement covers accepted units including RPM in specialized engineering contexts.
- ISO 80000-3, Space and Time formalizes angular velocity and its relationship between radians per second and revolutions.
Where frequency units appear
Converting a motor’s RPM rating into radians per second for a robotics or control systems equation, checking whether a processor’s clock speed in GHz matches a spec sheet quoted in MHz, tuning musical instruments against a reference frequency in Hz, verifying that AC mains frequency assumptions line up between 50 Hz and 60 Hz regions for imported electronics, and translating a wind turbine or engine tachometer reading into the angular velocity units used in an engineering calculation.
FAQ: Frequency Converter
Divide the hertz value by 1,000 to get kilohertz, since kilo means one thousand. For example, 2,500 Hz equals 2.5 kHz. Going the other direction, multiply kilohertz by 1,000 to get back to hertz.
Both are metric multiples of hertz: 1 megahertz (MHz) equals 1,000,000 Hz, while 1 gigahertz (GHz) equals 1,000,000,000 Hz, a thousand times larger than a megahertz. GHz is the typical unit for modern CPU clock speeds and Wi-Fi bands, while MHz is more common for older processors, FM radio frequencies, and many analog electronics specs.
RPM (revolutions per minute) and Hz (cycles per second) both measure repeating events, just over different time windows, so 1 Hz equals 60 RPM, since there are 60 seconds in a minute. This conversion is common when comparing a motor’s RPM rating to an electrical frequency spec, or when analyzing vibration frequencies from rotating machinery.
Radians per second (rad/s) is the standard unit of angular velocity in physics, engineering, and control systems, describing how fast an angle changes over time using radians (where a full circle is 2π radians) rather than revolutions. It converts to Hz by dividing by 2π, since one full revolution (2π radians) corresponds to one cycle.
Audible sound spans roughly 20 Hz to 20,000 Hz (20 kHz), the range of human hearing, while radio waves used for broadcasting and wireless communication span from kilohertz up into the gigahertz range, far above what any ear can perceive. The unit prefixes exist precisely because these fields routinely work across vastly different orders of magnitude.
Yes, all conversions use exact mathematical relationships between units (powers of 1,000 for metric prefixes, 60 for RPM, and 2π for radians), computed with full floating-point precision in your browser, not rounded lookup tables. For extremely high-precision engineering work, always cross-check against your specific standard’s defined constants.
From the blog
Reading around units
Where measurement systems came from and why two of them still argue.
