Frequency from Period Calculator
Convert oscillation period to frequency using f = 1/T. Enter the time for one complete cycle in seconds to find the corresponding frequency in hertz for waves, pendulums, or circuits.
How to use this tool
- Enter period (t) in the fields above.
- Results update instantly as you type — or click Calculate.
- Read your frequency and the full breakdown beneath it.
Formula
f = 1 / T
How it works
Frequency is the reciprocal of period: f = 1/T.
Worked example
Common mistakes to avoid
- Entering period in milliseconds instead of seconds — if T = 20 ms, you must enter 0.02 s to get a frequency in hertz; entering 20 gives a frequency 1000 times too low.
- Confusing period with half-period in oscilloscope measurements — if you measure the time from peak to trough (half-cycle), that is T/2; use the full cycle time for this calculator.
- Rounding the period aggressively before dividing — even small errors in T cause disproportionate errors in f when T is very small.
Key terms
Frequently asked questions
- What frequency corresponds to a period of 1 microsecond?
- f = 1 / (1 x 10^-6) = 1,000,000 Hz = 1 MHz. This is in the AM radio frequency range.
- How do I find the period from an oscilloscope?
- Measure the time between two consecutive rising (or falling) edges, or between two consecutive peaks. That time span is the period T. Then f = 1/T.
- Is this formula exact or approximate?
- It is exact for any perfectly periodic signal: f = 1/T with no approximation. For real signals with slight jitter or drift, the measured T represents an average, so f is an average frequency.