Menstrual Period Calculator — Predict Your Next Cycle
Predict your next 6 period dates instantly. Track your menstrual cycle length, know when to expect your period — no login needed.
Reviewed by Dr. Rukkayal Fathima, MRCOG (UK)
Typical: 21–35 days
Typical: 3–7 days
Understanding Your Menstrual Cycle
Your menstrual cycle is counted from the first day of one period to the first day of the next. The average cycle is 28 days, but anywhere between 21 and 35 days is considered normal for adults.
Each cycle has four phases: menstruation (your period, typically 3–7 days), the follicular phase (when an egg develops inside a follicle in the ovary), ovulation (when the mature egg is released, usually around day 14), and the luteal phase (when the body prepares the uterine lining for possible pregnancy). If pregnancy doesn't occur, hormone levels drop and the lining sheds — starting your next period.
Tracking your cycle helps you understand your body, plan ahead, and recognise changes early. If your cycles are consistently irregular — varying by more than 7 days from month to month — it could indicate conditions like PCOS, thyroid imbalances, or other hormonal issues that benefit from specialist evaluation.
When to See a Doctor About Your Periods
Most women experience some variation in their menstrual cycle. However, certain patterns warrant a consultation with a gynaecologist:
- Absent periods — no period for 3 or more months (when not pregnant or breastfeeding)
- Very heavy bleeding — soaking through a pad or tampon every 1–2 hours, or periods lasting longer than 7 days
- Severe pain — cramps that prevent daily activities or worsen over time
- Irregular cycles — cycle length varying by more than 7 days consistently, or fewer than 8 periods per year
- Bleeding between periods — spotting or bleeding outside your regular period
In India, conditions like PCOS affect 1 in 5 women of reproductive age. Early diagnosis and treatment — including lifestyle changes, medication, or fertility support — can significantly improve outcomes. If you notice any of these patterns, a specialist evaluation provides clarity and peace of mind.
Frequently Asked Questions
A period calculator uses the first day of your last menstrual period and your average cycle length to predict future period dates. It adds your cycle length repeatedly to estimate when your next periods will start.
A normal cycle ranges from 21 to 35 days, with 28 days being the average. Cycles that are consistently shorter than 21 or longer than 35 days may warrant a consultation with a gynaecologist.
Irregular periods can be caused by stress, weight changes, PCOS (polycystic ovary syndrome), thyroid disorders, or hormonal imbalances. If your periods are frequently irregular, consult a specialist for evaluation.
No, this calculator only predicts period dates based on cycle length. However, if you notice your cycles are consistently irregular (varying by more than 7 days), try our PCOS Symptom Checker for a preliminary assessment.
A normal period lasts 3 to 7 days. Bleeding that consistently lasts longer than 7 days or is very heavy (soaking through a pad every hour) should be evaluated by a doctor.
Minor variations of 1-2 days between cycles are normal. However, if your cycle length varies by more than 7 days from month to month, it may indicate an underlying hormonal issue.
See a doctor if your periods are consistently irregular, very heavy, extremely painful, absent for more than 3 months (when not pregnant), or if you experience bleeding between periods.
Yes. Dr. Rukkayal Fathima is a qualified gynaecologist (MS OBG, MRCOG UK) who diagnoses and treats menstrual disorders including irregular periods, heavy bleeding, PCOS, and endometriosis at her Chennai clinics.
Concerned About Your Cycle?
Dr. Rukkayal Fathima specialises in diagnosing and treating menstrual disorders, PCOS, and hormonal imbalances.
We welcome patients from Chennai and across India. Book an in-person visit or a video consultation.