Room for ChanceWhat it measures and where it is used
Frequency counts cycles per second. Hertz, named after Heinrich Hertz, is used for sound, electronics and alternating signals. RPM counts rotations per minute, so divide by 60 to obtain cycles per second. Angular frequency in radians per second is a different quantity.
- Classification
- SI derived quantity
- SI unit
- Hz = s⁻¹
- Dimension
- T⁻¹
L: length; M: mass; T: time; Θ: temperature; N: amount of substance. The dimension symbol N is not the unit symbol for newton.
How it works
The calculation first converts to a common reference unit, then to the destination unit. Factors in the table show the reference value for one unit.
Example
60 rpm ≈ 1 Hz
Available units
Reference unit: Hz
| Available units | Reference factor |
|---|---|
| Hz | 1 × x |
| kHz | 1,000 × x |
| MHz | 1,000,000 × x |
| GHz | 1,000,000,000 × x |
| rpm | 0.0166666666667 × x |
Units, history and conventions
The International System of Units (SI) received its name in 1960. Since the 2019 revision, its definitions use fixed values of seven defining constants. SI base and derived quantities should not be confused with the different units used to express them.