Predict your next periods, ovulation date and fertile window — track up to 6 future cycles from your last period date and average cycle length.
Enter your figures and click Calculate to see your results.
Enter your last period start date, average cycle length and period duration — then set how many future cycles to predict.
Press the Calculate button. Results appear instantly using standard clinical and scientific formulas.
Results are displayed with all key values clearly labelled. Use the Copy button to grab your results or Download to save a text file. For health decisions, always consult a healthcare professional.
A normal menstrual cycle ranges from 21 to 35 days, with 28 days being the average but not a universal standard. Cycle length varies naturally between individuals. A cycle is considered irregular if it varies by more than 7–9 days from cycle to cycle, is consistently shorter than 21 days or longer than 35 days.
The cycle has four phases: Menstruation (days 1–5 average): uterine lining sheds. Follicular phase (days 1–13): follicles develop, oestrogen rises. Ovulation (around day 14): egg is released. Luteal phase (days 15–28): progesterone rises to prepare the uterus; if no fertilisation, levels drop and the cycle restarts.
Yes. Psychological stress activates the HPA axis, suppressing hormones that regulate the menstrual cycle. Significant stress can delay ovulation, cause lighter or heavier periods, or stop periods entirely (hypothalamic amenorrhoea). Physical stressors — extreme exercise, severe illness or dramatic weight loss — have similar effects on hormonal regulation.
Spotting (light bleeding between periods) has many potential causes: ovulation spotting (normal, light spotting around ovulation), hormonal fluctuations, hormonal contraceptives, cervical irritation, polyps, fibroids, thyroid issues or, rarely, more serious conditions. Occasional spotting is often benign, but persistent or heavy irregular bleeding should be evaluated by a doctor.
Cycle tracking helps you predict periods and plan around them, identify your fertile window for conception or contraception, spot irregularities that may signal health issues, understand hormonal patterns affecting mood and energy, and provide accurate cycle information to healthcare providers when needed.
