Frequency ConverterFree online other calculator — instant results, no sign-up
Convert standard frequency units.
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About the Frequency Converter
The Frequency Converter converts a frequency value between hertz (Hz), kilohertz (kHz), and revolutions per minute (rpm). It uses Hz as the common basis, with rpm conversions treating one cycle as one revolution. With the default inputs of 1 Hz converted to rpm, the result is 60 rpm.
- Value
- The numerical frequency to convert, expressed in the selected From unit and defaulting to 1.
- From
- The source unit for Value: Hz (cycles per second), kHz (thousands of cycles per second), or rpm (revolutions per minute), defaulting to Hz.
- To
- The destination unit for the result: rpm (revolutions per minute), kHz (thousands of cycles per second), or Hz (cycles per second), defaulting to rpm.
Formula and method
y = x × c_from / c_to, where c_Hz = 1, c_kHz = 1000, and c_rpm = 1/60. For the default inputs: y = 1 × 1 / (1/60) = 60 rpm.
- xThe numerical frequency entered in Value.
- yThe converted numerical frequency in the selected To unit.
- c_fromThe number of Hz per unit of the selected From unit.
- c_toThe number of Hz per unit of the selected To unit.
- c_HzThe Hz conversion factor: 1 Hz per Hz.
- c_kHzThe kHz conversion factor: 1000 Hz per kHz.
- c_rpmThe rpm conversion factor: 1/60 Hz per rpm, assuming one cycle per revolution.
First multiply Value by the source unit's conversion factor to express the frequency in Hz. Then divide by the destination unit's conversion factor. With Value = 1, From = Hz, and To = rpm, the intermediate frequency is 1 Hz; dividing by 1/60 gives 60 rpm.
Worked example
These are the calculator's starting values and the results it actually produces for them.
Inputs
- Value1
- FromHz
- Torpm
Results
- Result60 rpm
How to use the Frequency Converter
- 1Enter the frequency in Value; keep 1 to follow the default example.
- 2Select the unit of the entered frequency in From; keep Hz for the default example.
- 3Select the desired output unit in To; keep rpm for the default example.
- 4Read the converted Result and its unit: the default inputs produce 60 rpm.
Reading your result
The Result row shows the entered frequency expressed in the selected To unit. For the default inputs, Result = 60 rpm means 1 cycle per second corresponds to 60 revolutions per minute when each cycle represents one revolution. The unit changes, not the underlying rate.
Limitations
This tool performs unit conversion only; it does not model motors, gearing, or sensor behavior. Converting Hz to rpm assumes one cycle per revolution, so electrical frequencies or pulse signals with multiple cycles or pulses per revolution require an additional relationship. Conversion factors are exact, but displayed results may be rounded. A negative value is not ordinarily a physical frequency magnitude, even if a signed calculation is allowed.
Common questions
Why does 1 Hz convert to 60 rpm?+
Hz measures cycles per second, while rpm measures revolutions per minute. With one cycle per revolution and 60 seconds per minute, 1 Hz corresponds to 60 rpm.
How does the calculator convert between kHz and Hz?+
It multiplies by 1000 when converting kHz to Hz and divides by 1000 when converting Hz to kHz.
Can I use a motor's electrical frequency in Hz to find its shaft rpm?+
Not directly in general. Shaft speed depends on the motor type and pole count, and induction motors also have slip. This converter uses only the one-cycle-per-revolution relationship.
Is rpm the same as radians per second?+
No. rpm counts complete revolutions per minute, while radians per second measures angular speed. This calculator supports rpm, Hz, and kHz, not radians per second.
Does the calculator save my information?+
Calculations run in your browser. While signed in, inputs and results are automatically recorded in account history; saving a result creates a separate saved record.
Further reading
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Results are estimates for informational purposes and are not financial, medical or legal advice.