Frequency Converter
Frequency measures how often something repeats in a given amount of time, such as the number of cycles, vibrations, or rotations that occur each second. It is one of the most widely used quantities in science and engineering, describing everything from the pitch of a sound and the speed of a computer processor to the wobble of an electrical grid and the spin of a motor shaft.
All Frequency Conversions
People convert frequency units because different fields use different scales. A musician thinks in hertz, an electrician in cycles per second, a mechanic in revolutions per minute, and a robotics engineer in radians per second. Converting between them lets you compare values that describe the same underlying motion or signal in units that suit the task at hand.
Frequency Units Explained
The base SI unit is the hertz (Hz), defined as one cycle per second. Decimal prefixes scale it: 1 millihertz (mHz) = 0.001 Hz, 1 kilohertz (kHz) = 1,000 Hz, 1 megahertz (MHz) = 1,000,000 Hz, 1 gigahertz (GHz) = 1,000,000,000 Hz, and 1 terahertz (THz) = 1,000,000,000,000 Hz. These cover audio, radio, and processor speeds. Rotational units describe spinning motion: revolutions per minute (rpm), degrees per second (deg/s), and radians per second (rad/s). One full revolution equals 360 degrees or 2 pi radians, which links these angular units directly to cycles per second.
How to Convert Frequency Units
Convert by routing through hertz (cycles per second) as the base unit. For decimal prefixes, multiply by the prefix factor: to go from GHz to Hz, multiply by 1,000,000,000 (so 2.4 GHz = 2,400,000,000 Hz). For rotational units, use the fact that one cycle is one revolution: 1 Hz = 60 rpm, 1 Hz = 2 pi rad/s, and 1 Hz = 360 deg/s. So to convert rpm to Hz, divide by 60. Example: a turntable at 33 1/3 rpm spins at 33.333 / 60 = 0.5556 Hz. To convert that to radians per second, multiply by 2 pi: 0.5556 x 2 pi = 3.49 rad/s. Going the other way, 1 rad/s = 1 / (2 pi) = 0.15915 Hz.
Common Uses
- Comparing CPU and memory clock speeds in MHz and GHz
- Tuning musical instruments to a reference pitch in Hz
- Setting motor or fan speed in rpm and rad/s
- Matching electrical grid frequency (50 Hz vs 60 Hz)
- Specifying radio and Wi-Fi bands in MHz and GHz
- Programming servo and stepper motor speeds in deg/s
Accuracy Tips
Keep cycle-based units (Hz, kHz, rpm) and angle-based units (rad/s, deg/s) straight: one cycle equals 2 pi radians, not 1. A common mistake is treating 1 Hz as 1 rad/s; it is actually about 6.283 rad/s. Also remember rpm is per minute, so divide by 60 to reach per-second units. When precision matters, carry the full value of pi rather than rounding early.
Frequently Asked Questions
How do you convert rpm to Hz?
Divide the rpm value by 60, because there are 60 seconds in a minute. For example, 1,800 rpm = 1,800 / 60 = 30 Hz. To go back, multiply hertz by 60: 30 Hz = 1,800 rpm.
What is 1 Hz in radians per second?
One hertz equals 2 pi radians per second, which is about 6.2832 rad/s, because a full cycle sweeps through 2 pi radians. Conversely, 1 rad/s equals 1 / (2 pi) = about 0.15915 Hz.
How many Hz are in a GHz?
One gigahertz equals 1,000,000,000 (one billion) hertz. A 3 GHz processor therefore completes about 3 billion clock cycles per second. One GHz also equals 1,000 MHz.
What is the difference between Hz and rpm?
Both measure how often something repeats, but hertz counts cycles per second while rpm counts revolutions per minute. Since one revolution is one cycle, 1 Hz = 60 rpm and 1 rpm = 1/60 Hz (about 0.01667 Hz).
How do you convert degrees per second to rpm?
Divide deg/s by 6, since one revolution is 360 degrees and there are 60 seconds per minute (360 / 60 = 6 deg/s per rpm). For example, 90 deg/s = 90 / 6 = 15 rpm.