Period Calculator: Predict Your Next 6 Periods
Enter the first day of your last period, your cycle length and how long your period lasts to see your next 6 periods.
- Nothing you type is stored
- Free
- No signup
Next period expected
Wed, 2 Dec 2026
- Period expected to end
- Sun, 6 Dec 2026
- Days until next period
- 28 days
- Estimated ovulation
- Wed, 18 Nov 2026
An estimate for general information, not medical advice. Calendar dates are not reliable birth control; see a doctor if your cycles change a lot.
Predictions assume a regular cycle. A few days early or late is normal.
Next 6 cycles
| Starts | Ends | Fertile from | Ovulation | Fertile to |
|---|---|---|---|---|
| Wed, 2 Dec 2026 | Sun, 6 Dec 2026 | Fri, 11 Dec 2026 | Wed, 16 Dec 2026 | Thu, 17 Dec 2026 |
| Wed, 30 Dec 2026 | Sun, 3 Jan 2027 | Fri, 8 Jan 2027 | Wed, 13 Jan 2027 | Thu, 14 Jan 2027 |
| Wed, 27 Jan 2027 | Sun, 31 Jan 2027 | Fri, 5 Feb 2027 | Wed, 10 Feb 2027 | Thu, 11 Feb 2027 |
| Wed, 24 Feb 2027 | Sun, 28 Feb 2027 | Fri, 5 Mar 2027 | Wed, 10 Mar 2027 | Thu, 11 Mar 2027 |
| Wed, 24 Mar 2027 | Sun, 28 Mar 2027 | Fri, 2 Apr 2027 | Wed, 7 Apr 2027 | Thu, 8 Apr 2027 |
| Wed, 21 Apr 2027 | Sun, 25 Apr 2027 | Fri, 30 Apr 2027 | Wed, 5 May 2027 | Thu, 6 May 2027 |
How to use
- Enter the first day of your last period.
- Enter your usual cycle length and period length.
- See your next period, days to go and a 6-cycle calendar.
Good to know
Next period = first day of the last period + cycle length, repeated for each cycle. Ovulation is estimated 14 days before each period and the fertile window as the 5 days before to 1 day after.
A normal cycle for adults is 21–35 days, and periods usually last 2–7 days. It is common for cycles to vary by a few days from month to month. Tracking 3–6 months of dates gives a better average cycle length to enter here.
See a doctor if your periods are often shorter than 21 or longer than 35 days, stop for 3 months (and you are not pregnant), are very heavy, or come with severe pain. These can be signs of conditions such as PCOS, thyroid problems or anaemia, which are common and treatable.
Questions
How do I calculate my next period?
Add your cycle length to the first day of your last period. With a 28-day cycle and a period starting on 1 March, the next is due around 29 March.
What is a normal cycle length?
Between 21 and 35 days for most adults; 28 is only an average.
My period is late. Am I pregnant?
It is possible. Take a home pregnancy test if your period is a week late, and see a doctor if it is positive or if periods keep missing.
Why are the dates different from my app?
Apps may use your own history. Enter your average cycle length for the closest match.
Is my data saved?
No. Your dates stay on your device; nothing is stored or sent.