ConverterHub

Frequency to Period Calculator

Convert frequency to period.

How it is calculated

The period of a repeating signal is the inverse of its frequency: T = 1 / f. Frequency f is entered in hertz (cycles per second) and the period T comes out in seconds. The frequency must be greater than zero. The result is rounded to two decimals, so high frequencies show 0.00 s: 50 Hz is displayed as 0.02 s and 1 kHz as 0.00 s. For such signals convert to milliseconds or microseconds yourself, for example 1 / 1000 Hz = 0.001 s = 1 ms. Enter kilohertz or megahertz values as hertz (1 kHz = 1000 Hz, 1 MHz = 1,000,000 Hz).

Worked example

A signal repeats 4 times each second, so f = 4 Hz. The period is T = 1 / 4 = 0.25 s. Each cycle takes a quarter of a second, and doubling the frequency to 8 Hz would halve the period to 0.125 s, which the two-decimal display would round to 0.13 s.

Try this example →

Common mistakes

  • Entering kilohertz or megahertz as if it were hertz; 50 kHz must be typed as 50000.
  • Expecting milliseconds: the answer is in seconds and the two-decimal rounding hides small periods.
  • Reading 0.00 s as zero when the real period is just very short.
  • Typing zero frequency; the period of a constant signal is undefined.
  • Confusing frequency in hertz with angular frequency in radians per second, which is 2π times larger.

About this calculator

This calculator applies the inverse relationship T = 1/f, where period (T, in seconds) is the time for one complete wave cycle and frequency (f, in Hertz) is how many cycles occur per second — doubling the frequency always halves the period, and vice versa. It works across any oscillating signal, from AC electrical current at 50 or 60 Hz to a microprocessor clock running at gigahertz speeds.

Electrical engineers checking a circuit's timing, programmers setting up a timer or PWM signal that's specified in Hertz but needs to be coded in milliseconds, and physics students converting between the two units in wave problems all use this same formula.

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