Frequency to Period Calculator — T = 1/f (Free Online)

Convert Hz to seconds, ms, µs, or ns — and period back to frequency

Target Variable

Required Parameters

Frequency

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Quick Answer

Period T = 1 / f. Example: 1 MHz → 1 µs period; 60 Hz mains → 16.67 ms; 1 GHz → 1 ns. Enter period to get frequency: f = 1/T.

Documentation

Frequency to Period Calculator

Convert frequency to period instantly with T = 1/f — enter Hz, kHz, MHz, or GHz and get period in seconds (auto-scaled to ms, µs, or ns). Switch to Frequency (from period) to solve the reverse.

Quick start: Select Period, enter frequency (e.g. 1 MHz) → result shows 1 µs. Select Frequency (from period), enter 16.67 ms → 60 Hz.

Frequency to period formula

T = 1 / f

Symbol	Unit	Meaning
T	seconds (s)	Time for one complete cycle
f	hertz (Hz)	Cycles per second

Reverse: f = 1 / T

Common conversions

Frequency	Period
60 Hz (mains US)	16.67 ms
50 Hz (mains EU)	20 ms
1 kHz	1 ms
1 MHz	1 µs
1 GHz	1 ns
2.4 GHz (WiFi)	417 ps

Worked example

Find period of 100 MHz clock:

T = 1 / 100,000,000 = 10 ns
Half-period (for edge timing) = 5 ns

Period vs wavelength

Period is time per cycle; wavelength is distance per cycle:

λ = c × T = c / f

For RF wavelength with velocity factor, use the Frequency to Wavelength Calculator.

Related tools

Frequency to Wavelength Calculator — λ = c/f with velocity factor
555 Timer Calculator — astable period from R and C
RC Time Constant Calculator
Reactance Calculator

Design Notes

Never assume signals travel at the speed of light over a PCB or through a coaxial cable. For example, standard FR4 PCB material has a VF of roughly 0.45 to 0.55 depending on the trace geometry. This means a 1 GHz signal, which has a 30 cm wavelength in air, will only have a ~15 cm wavelength on your PCB. If you are designing quarter-wave matching stubs or length-matching high speed lines, using the correct velocity factor is critical.

Common Mistakes

1
Using c (300,000 km/s) for calculations inside coax cables. RG-58 coax typically has a VF of 0.66, meaning the wave is 34% slower.
2
Confusing Hz with MHz/GHz resulting in calculation errors off by millions. Always use base SI units or keep track of the scientific notation.
3
Ignoring the effect of dielectric loading. Exposing a trace to air vs encapsulating it in conformal coating changes the local velocity factor.

Engineering Handbox

1. Convert Frequency: 2.4 GHz = 2,400,000,000 Hz 2. Base Wavelength (Air): λ = c / f = 299,792,458 / 2.4e9 = 12.49 cm 3. Apply Velocity Factor: 12.49 cm × 0.66 = 8.24 cm

VerificationThe wavelength inside the RG-58 coax is 8.24 cm. A quarter-wave stub should be ~2.06 cm.

Knowledge Base

What is the frequency to period formula?

Period T = 1 / f, where T is in seconds and f is in hertz (Hz). One hertz equals one cycle per second, so the period is the time for one complete cycle. Rearranged: f = 1 / T.

How do I convert MHz to period in microseconds?

T (µs) = 1 / f (MHz). Example: 1 MHz → 1 µs; 10 MHz → 100 ns; 100 MHz → 10 ns. For Hz: T (s) = 1/f. The calculator auto-scales to the best time unit.

What is the period of 60 Hz AC mains?

T = 1/60 = 16.67 ms per cycle. In the US and most of the Americas, mains is 60 Hz. In Europe and much of Asia it is 50 Hz → 20 ms period.

What is the difference between period and frequency?

Frequency (Hz) counts how many cycles occur per second. Period (seconds) is the duration of one cycle. They are reciprocals: doubling frequency halves the period.

How is period related to wavelength?

For electromagnetic waves: λ = c × T = c / f, where c is the speed of light. Period and wavelength describe the same wave — period in time, wavelength in space. Use our frequency-wavelength calculator when you need λ.

What period does a 555 timer astable output?

Period T = 0.693 × (R1 + 2×R2) × C for a standard NE555 astable. Frequency f = 1/T. Example: R1=1k, R2=680k, C=1µF → T ≈ 0.94 s (~1.06 Hz). See our 555 timer calculator for duty cycle.

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