Choose a Measurement
Select a measurement and convert between different units
Single conversion
To convert from rotation per minute (rpm) to millihertz (mHz), use the following formula:
Let's convert 5 rotation per minute (rpm) to millihertz (mHz).
Using the formula:
Therefore, 5 rotation per minute (rpm) is equal to millihertz (mHz).
Here are some quick reference conversions from rotation per minute (rpm) to millihertz (mHz):
| rotations per minute | millihertz |
|---|---|
| 0.000001 rpm | mHz |
| 0.001 rpm | mHz |
| 0.1 rpm | mHz |
| 1 rpm | mHz |
| 2 rpm | mHz |
| 3 rpm | mHz |
| 4 rpm | mHz |
| 5 rpm | mHz |
| 6 rpm | mHz |
| 7 rpm | mHz |
| 8 rpm | mHz |
| 9 rpm | mHz |
| 10 rpm | mHz |
| 20 rpm | mHz |
| 30 rpm | mHz |
| 40 rpm | mHz |
| 50 rpm | mHz |
| 100 rpm | mHz |
| 1000 rpm | mHz |
| 10000 rpm | mHz |
For all Frequency converters, choose units using the From/To dropdowns above.
Simply put, rotations per minute (RPM) measures the speed at which something is spinning.
It counts the number of full turns an object completes in one minute. From car engines to computer hard drives, RPM is a key indicator of performance and speed.
The concept of RPM (rotations per minute) gained popularity during the Industrial Revolution, thanks in large part to Scottish engineer James Watt.
While developing his steam engine, Watt needed a way to compare its power output to that of a horse. To do this, he determined how many times a horse could turn a mill wheel in one minute.
He utilized this rotational measurement to help establish the definition of horsepower. As a result, RPM became a crucial metric for quantifying the performance and work capacity of mechanical engines—a practice that continues to this day.
You encounter RPM every day in common technology.
In your car, the tachometer displays the engine's speed in rotations per minute, indicating how fast the crankshaft is spinning. A higher RPM generally means more power is being produced.
Computer hard disk drives (HDDs) also use RPM to measure their performance; a 7200 RPM drive can read and write data faster than a 5400 RPM drive.
RPM ratings, which denote motor speed and efficiency, are also found on household appliances such as blenders, washing machines, and fans.
Although RPM is a common unit, physics and engineering often use hertz (Hz) for frequency and radians per second (rad/s) for angular velocity.
The conversion is straightforward:
To Hertz (Hz): Because a minute has 60 seconds, you divide the RPM value by 60.
To Radians per Second (rad/s): One complete rotation is equivalent to 2π radians. To convert RPM to radians per second, multiply the RPM value by 2π, then divide by 60.
Ever wondered how scientists measure incredibly slow, barely-there movements, like the subtle shifting of continents or the rhythm of a distant star?
They often use a special unit of frequency called the millihertz (mHz).
A millihertz is a unit of frequency equal to one-thousandth of a hertz (0.001 Hz). It's designed to measure things that happen very, very slowly.
While a standard hertz (Hz) measures cycles per second (think sound waves or computer speeds), a millihertz measures events that occur very slowly, taking a very long time to complete a single cycle.
To put it in perspective, something oscillating at one mHz takes 1,000 seconds—or nearly 17 minutes—to complete just one cycle!
This makes the unit perfect for tracking extremely slow phenomena.
Key applications include:
Frequency and time are two sides of the same coin.
In physics, the time it takes for one complete cycle is called the period (T), while frequency (f) refers to the number of cycles that occur per second. They are inversely related: as one increases, the other decreases.
The relationship is expressed as T = 1/f.
To find the period in seconds from a frequency in mHz, you first convert mHz to Hz (1 mHz = 0.001 Hz) and then find its reciprocal.
Formula:
Example:
The mHz range is crucial for one of the most exciting fields in modern astronomy: the search for gravitational waves.
Space-based observatories, such as the Laser Interferometer Space Antenna (LISA), are specifically designed to detect low-frequency gravitational waves in the millihertz band.
These ripples in spacetime are believed to be caused by some of the most massive and dramatic events in the universe, such as:
Detecting signals in the millihertz band offers scientists a unique opportunity to explore cosmic events, allowing them to observe the universe in a completely new way.