How to use the frequency converter
- Type a number in the From box. 44100 is entered for you, and decimals and commas both work, such as 2.4 or 44,100.
- Pick the unit you have in the first menu and the unit you want in the second. Hz, kHz, MHz, GHz and THz sit beside BPM, RPM, rad/s and degrees per second.
- To work backwards, type in the To box instead.
- Read the Period line for the length of one cycle, or press Swap units to flip the direction.
How the conversion works
The hertz is one cycle per second, as defined in the NIST Guide to the SI, Chapter 4, and kilo, mega, giga and tera each multiply by 1,000. The tool stores every unit as a size in hertz and computes result = value × From size ÷ To size. BPM and RPM both count events per minute, so each is 1/60 Hz. Angular frequency in rad/s is the frequency times 2π, so 1 Hz is 6.2831853 rad/s. The period is T = 1 ÷ f, shown in the unit that reads best, from days to femtoseconds. Answers show up to 10 significant digits.
Worked example with the default values
With 44100 in the From box, Hertz (Hz) as the From unit and Kilohertz (kHz) as the To unit, the result line reads 44,100 Hz = 44.1 kHz, because 44,100 ÷ 1,000 = 44.1. The reverse line reads 1 kHz = 1,000 Hz, and the period line reads Period: 22.676 µs per cycle (1 ÷ 44,100 Hz), because 1 ÷ 44,100 is 0.000022676 seconds. That is the CD audio sample rate.
BPM to Hz and beat length
| Tempo | Frequency | One beat lasts |
|---|---|---|
| 60 BPM | 1 Hz | 1,000 ms |
| 100 BPM | 1.6667 Hz | 600 ms |
| 120 BPM | 2 Hz | 500 ms |
| 128 BPM | 2.1333 Hz | 468.75 ms |
| 174 BPM | 2.9 Hz | 344.83 ms |
Common frequencies
| What | Frequency |
|---|---|
| Concert pitch A4 | 440 Hz |
| US mains power | 60 Hz |
| Human hearing | 20 Hz to 20 kHz |
| FM radio, US | 88 to 108 MHz |
| Wi-Fi | 2.4 GHz and 5 GHz |
| Visible light | roughly 430 to 750 THz |
To set a tempo, use the metronome. For rad/s in degrees or turns, use the angle converter, and for very large or small values such as THz, the scientific notation converter. The unit converter covers other kinds of unit.
Limits and edge cases
Negative values convert normally, which can describe a shaft turning the other way. The Period line appears only above 0 Hz, because 0 Hz has no cycle length. Letters, currency symbols and slashes are blocked with a hint, and numbers above 1,000,000,000,000,000,000,000,000 are refused. This tool does not turn a frequency into a wavelength, because that needs the speed of the wave.
Sources: NIST Guide to the SI, Chapter 4; ISO 16:1975, Standard tuning frequency.
Frequency Converter FAQ
How do I convert BPM to Hz?
Divide the BPM by 60. 120 BPM is 2 Hz, so one beat lasts 500 ms (60,000 divided by the BPM). That time is also the delay setting for a quarter note.
How do I convert RPM to Hz?
Divide the RPM by 60 as well. A motor at 1,800 RPM turns 30 times per second, which is 30 Hz, and a 3,000 RPM shaft turns at 50 Hz.
How many Hz are in a kHz, MHz and GHz?
1 kHz is 1,000 Hz, 1 MHz is 1,000,000 Hz and 1 GHz is 1,000,000,000 Hz. Each step up multiplies by 1,000, and a terahertz (THz) is 1,000 GHz.
How do I get the period from a frequency?
Divide 1 by the frequency in hertz. The answer is in seconds. At 44,100 Hz the period is 22.676 µs, and at 2.4 GHz it is about 416.67 ps.
What frequency is concert A?
The A above middle C (A4) is tuned to 440 Hz, the standard pitch set in ISO 16.