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Frequency and time period calculator

GCSEA-level Waves

Frequency is the number of waves per second, and the period is the time for one wave.

f = 1 / T

This free calculator is for GCSE and A-level physics. Choose the quantity you want to find, enter the other values with their units, and it shows the working in the layout used in exams, with the answer to the number of significant figures you choose. The values shown are an example. Change them to your own.

Quantity to find

250 Hz

Working

  1. Write the equation
    f = 1 / T
  2. Substitute the values
    f = 1 ÷ 0.004
  3. Calculate
    f = 250 Hz
  4. Give the answer to 3 significant figures
    f = 250 Hz

Worked example

Find f, the frequency. Given: time period T = 0.00400 s.

  1. Write the equation
    f = 1 / T
  2. Substitute the values
    f = 1 ÷ 0.004
  3. Calculate
    f = 250 Hz
  4. Give the answer to 3 significant figures
    f = 250 Hz

Symbols and units

SymbolQuantitySI unit
fFrequencyHz
TTime periods

Frequency and time period: rearranged

  • To find frequency: f = 1 / T
  • To find time period: T = 1 / f

Exam tip

If the period is in milliseconds, use the unit selector or convert to seconds first.

Common questions

What is the formula for frequency and time period?

The equation is f = 1 / T, where f is the frequency (Hz); T is the time period (s).

What units should I use for frequency and time period?

In SI units: frequency in Hz, time period in s. The calculator also accepts common alternatives such as kilometres, grams or minutes, and converts them for you.

How do I rearrange f = 1 / T?

Rearranging gives these forms: to find frequency: f = 1 / T. to find time period: T = 1 / f.

Practise frequency and time period questions

Press the button for a question with random numbers. Work it out on paper first, then type your answer.

Related

More waves equations: Wave speed, Magnification, Refractive index, Snell’s law, Critical angle, Double-slit fringe spacing, Diffraction grating, Intensity. See the full list on the physics equation calculator page.