Enter your last period date and press Calculate to see your cycle predictions.
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Period calculator — frequently asked
How does the period calculator work?
Enter the first day of your last period and your average cycle length (28 days is typical for Indian women, but 21-35 days is also normal). The calculator counts forward to predict your next 6 period start dates, plus the ovulation day and fertile window within each cycle. The prediction assumes a roughly regular cycle.
What's a normal menstrual cycle length?
Any cycle between 21 and 35 days is considered normal. The 28-day cycle is a popular average but not a universal standard. What matters more is consistency — if your cycle length varies by less than 7-9 days month-to-month, you're considered regular. Significant variation beyond that is irregular and worth discussing with a gynaecologist.
Does this period calculator work for irregular periods or PCOS?
It can give you a rough estimate but the prediction will be less accurate. With PCOS, post-pregnancy, perimenopause, or chronic stress, cycles often vary by 7+ days month-to-month. For irregular cycles, consider tracking 3-6 months of actual period dates to find your personal average, and don't rely on calendar predictions alone for contraception or conception planning.
What if my period is late?
A period is officially 'late' once you're 5+ days past your expected date. Common reasons include stress, sudden weight change, intense exercise, travel, hormonal changes, thyroid issues, PCOS, perimenopause, and (of course) pregnancy. If you're sexually active and your period is late, take a home pregnancy test 1-2 weeks after the missed period for the most accurate result.
Why am I getting my period twice in one month?
Shorter cycles (21-23 days) can occasionally produce two periods within a calendar month — that's normal if it's consistent. But unexpected bleeding between periods, very heavy or prolonged bleeding, or bleeding after intercourse can indicate hormonal imbalance, fibroids, polyps, or thyroid issues — book a gynaecologist appointment if it happens more than once.
Is this a substitute for a doctor?
No — it's a calendar tool. If you have heavy bleeding, severe pain, missed periods for 3+ months (when not pregnant), bleeding after menopause, or any new symptoms, see a gynaecologist. The calculator helps you track your cycle; it doesn't diagnose conditions.