Menstrual Calendar
A calendar of your periods, fertile days and PMS days. Free, private and instant.
How to use the Menstrual Calendar
- Pick first day of your last period.
- Enter average cycle length (days).
- Enter period length (days).
- Choose luteal phase (ovulation to next period): 10 days, 11 days, 12 days, 13 days and more.
- Choose months to show: 3 months, 6 months or 12 months.
- Press Calculate to get an instant result with a colour scale, chart and plain-English explanation.
About the Menstrual Calendar
The menstrual calendar plots your predicted periods, fertile window, ovulation day and likely PMS days across the next 3, 6 or 12 months so you can plan ahead for travel, events, exams or conception.
Also known as: period calendar, menstrual cycle calendar, cycle calendar, period and ovulation calendar.
Worked example
Dates in this example are worked out as if today were 5 Nov 2026.
- First day of your last period: 22 Oct 2026
- Average cycle length: 28 days
- Period length: 5 days
- Luteal phase (ovulation to next period): 14 days (typical)
- Months to show: 6 months
Today is cycle day: 15 of 28 (Ovulation window phase). You are on day 15 of a 28-day cycle, in the ovulation window phase. Your calendar below marks periods, the fertile window, ovulation and PMS days.
- Next period: 19 Nov - 23 Nov 2026
- Period 2: 17 Dec - 21 Dec 2026
- Period 3: 14 Jan - 18 Jan 2027
- Period 4: 11 Feb - 15 Feb 2027
Formula and cut-offs
Each cycle starts on a predicted period date. Period days = period length. Ovulation = cycle end - 14 days. Fertile days = 5 days before ovulation to 1 day after. PMS days = 5 days before the next period.
Frequently asked questions
How do I make a period calendar?
Enter the first day of your last period and your average cycle length. The calendar projects future cycles from that.
How far ahead can I predict?
Predictions get less accurate with each cycle, so update your last period date every month.
What are PMS days on the calendar?
The few days before your period when premenstrual symptoms are most likely.
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.