Frequency is a key concept in both science and engineering, with wide-ranging importance in areas like physics, telecommunications, and signal processing. At its most basic, frequency describes how many times a repeating event occurs over a certain period. It’s usually measured in Hertz (Hz), where one Hertz equals one cycle per second.
What Is Frequency?
In simple terms, frequency describes how often something happens within a given time frame. For instance, when it comes to sound waves, higher frequencies produce high-pitched tones, while lower frequencies result in deeper, bass-like sounds. In the world of electrical engineering, frequency plays a critical role in how alternating current (AC) systems function and how radio signals are transmitted. It's a fundamental concept for understanding wave behavior and making sure that electronic devices work properly and stay within their designated frequency ranges.
SI Frequency Units Conversion
Frequency is most commonly measured in Hertz (Hz), the official SI unit. However, depending on the size or scale of the signal or wave, it’s often helpful to convert frequency into smaller or larger units to simplify calculations. Below is a detailed breakdown of frequency units and their corresponding values in Hertz for easy reference.
Frequency Unit |
Value in Hertz (Hz) |
Picohertz (pHz) |
1 × 10⁻¹² Hz |
Nanohertz (nHz) |
1 × 10⁻⁹ Hz |
Microhertz (μHz) |
0.000001 Hz |
Millihertz (mHz) |
0.001 Hz |
Centihertz (cHz) |
0.01 Hz |
Decihertz (dHz) |
0.1 Hz |
Decahertz (daHz) |
10 Hz |
Hectohertz (hHz) |
100 Hz |
Kilohertz (kHz) |
1,000 Hz |
Megahertz (MHz) |
1,000,000 Hz |
Gigahertz (GHz) |
1 × 10⁹ Hz |
Terahertz (THz) |
1 × 10¹² Hz |
Revolutions per minute (RPM) |
0.0167 Hz |
Revolutions per hour (RPH) |
2.7 × 10⁻⁴ Hz |
Radians per second (rad/s) |
0.159155 Hz |
Degrees per second (deg/s) |
2.7 × 10⁻³ Hz |
How to Calculate Frequency
Calculating frequency might sound technical, but it’s actually pretty straightforward once you break it down. Whether you're working with sound, light, or machines, frequency tells you how often something repeats — and there are a couple of simple ways to figure it out.
Example 1: From Time Period to Frequency
One of the easiest ways to calculate frequency is by using the time it takes for one complete cycle — that’s called the time period. Here’s the basic formula:
f = 1 / T
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f is the frequency in Hertz (Hz)
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T is the time for one cycle, measured in seconds
Let’s say a sound wave takes 0.002 seconds to complete one cycle. Just plug it into the formula:
f = 1 / 0.002 = 500 Hz
So that wave is vibrating 500 times per second — which is pretty fast and would sound like a high-pitched tone to our ears.
Example 2: Converting RPM to Hertz
Now, let’s talk machines. Motors and engines often run in RPM (revolutions per minute), but sometimes you need to convert that to Hertz, especially in electrical and engineering work. Here’s how:
f = RPM / 60
If a motor spins at 3,600 RPM, divide that by 60:
f = 3600 / 60 = 60 Hz
That means it’s completing 60 full cycles per second, which is actually the standard frequency for electrical outlets in many parts of the world. Since electrical energy depends on both power and time, tools like the Power Converter can help you translate between watts, horsepower, and kilowatts in seconds.
Fun Facts About Energy
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Only 20–30% of the chemical energy in gasoline actually powers your car — the rest is lost as heat!
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The human body is an amazing biological converter. We turn food (chemical energy) into motion, heat, and even thoughts.
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A single square meter of Earth receives about 1,000 watts of solar energy on a sunny day — enough to power a blender.
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Your phone battery stores energy chemically and converts it to electrical energy. That simple act powers processors, screen, speakers, and more — all at once!
The Steam That Launched the Industrial Revolution
In the late 1600s, an inventor named Thomas Savery designed one of the first mechanical devices to convert thermal energy (from boiling water) into mechanical energy to pump water out of mines. It was a crude steam engine — no moving pistons, just pressurized steam pushing water upward. While it wasn't very efficient, it laid the groundwork for later improvements by James Watt, whose upgraded steam engine powered factories, trains, and ships. Because thermal energy is directly tied to temperature, you might find our Temperature converter helpful when comparing energy changes across Celsius, Fahrenheit, or Kelvin scales.
This wasn’t just a leap in technology. It marked a turning point in energy history — when humanity first learned to convert stored chemical energy (coal) into mechanical force on a mass scale.
And all of that… started with an energy converter.
If you're working across different units of measurement, our Conversion Tools offers a full suite of calculators to simplify the process — from energy and force to pressure and temperature.