Period Tracker and Next Period Calculator

Predict your next 3 periods and see your cycle phase. Free, private and instant.

How to use the Period Tracker

  1. Pick first day of your last period.
  2. Enter average cycle length (days).
  3. Enter period length (days).
  4. Press Calculate to get an instant result with a colour scale, chart and plain-English explanation.

About the Period Tracker

This period tracker and next period calculator predicts when your next three periods will start from the first day of your last period and your usual cycle length. It also shows your fertile window, ovulation day and which phase of the cycle you are in today, with a calendar and phase chart.

Also known as: period calculator, next period date, period predictor, when is my next period.

Worked example

Dates in this example are worked out as if today were 5 Nov 2026.

Days until your next period: 14 days (Next period 19 Nov 2026). Your next period is expected on Thu, 19 Nov 2026 and should last about 5 days (to 23 Nov 2026). Today is about day 15 of your cycle.

Formula and cut-offs

Next period = first day of last period + average cycle length. Ovulation = next period - 14 days (luteal phase). Fertile window = 5 days before ovulation to 1 day after. A typical cycle is 21 to 35 days.

Frequently asked questions

How do I calculate when my next period is due?

Add your average cycle length to the first day of your last period. For a 28-day cycle starting 1 March, the next period is expected about 29 March.

Why is my period late or early?

Stress, travel, illness, weight change, hormones, breastfeeding and pregnancy can all shift a period by several days.

What is a normal cycle length?

Most adults have cycles between 21 and 35 days. A cycle that varies by a few days each month is normal.

When is my next period if my last one started on 22 Oct 2026 and my cycle is 28 days?

Your next period is expected on Thu, 19 Nov 2026 and should last about 5 days (to 23 Nov 2026). Today is about day 15 of your cycle. This example treats 5 Nov 2026 as today. Enter your own dates above for a personal result.

Sources and references

Written and checked by the MediHub editorial team against the sources above. Read how we build and review our calculators.

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Last updated . This calculator is for education only and is not medical advice. See the medical disclaimer.