Track your menstrual cycle, predict your next period, ovulation day, and fertile window. Understand your body's natural rhythm with our interactive visual calendar and comprehensive cycle analysis.
Your fertile window is the 6-day period ending on ovulation day — this is when pregnancy is most likely to occur. Your next period is expected based on your average cycle length. The luteal phase (after ovulation) is typically consistent at 14 days for most women.
Enter your dates in the Calculator tab to see your personalized cycle calendar here.
The menstrual cycle has four phases: menstruation (period), the follicular phase (preparing an egg), ovulation (egg release), and the luteal phase (preparing for pregnancy). The average cycle is 28 days, but anything from 21–35 days is considered normal. Tracking your cycle helps you understand your unique pattern.
Ovulation is the release of a mature egg from the ovary, typically occurring once per cycle. The egg travels through the fallopian tube where it can be fertilized for about 12-24 hours. Ovulation is triggered by a surge in luteinizing hormone (LH) that occurs about 36 hours before the egg is released.
The fertile window spans approximately 6 days — the 5 days leading up to ovulation plus the day of ovulation itself. Sperm can survive for up to 5 days in the female reproductive tract, so having intercourse in the days before ovulation offers the best chance of conception.
The luteal phase occurs after ovulation and lasts about 14 days (ranging from 10-17 days). During this phase, the corpus luteum produces progesterone to thicken the uterine lining. If pregnancy doesn't occur, progesterone drops and the uterine lining sheds as your next period.
For a standard 28-day cycle with a 14-day luteal phase: ovulation occurs on cycle day 14. Your next period starts on cycle day 28 (the first day of the next cycle). The fertile window spans the 5 days before ovulation through ovulation day.
Fertility and period tracking apps help you log your cycle, predict future periods, and identify patterns over time. Many allow you to track symptoms, mood, flow intensity, and more. Combine app data with physical signs for the most accurate cycle awareness.
Take your temperature at the same time every morning before getting out of bed using a BBT thermometer (accurate to 0.01°F). After ovulation, your temperature rises 0.5-1°F and stays elevated until your next period. This confirms that ovulation has occurred.
Check your cervical mucus daily and note its appearance. Around ovulation, it becomes clear, slippery, and stretchy — similar to raw egg whites. This fertile-quality mucus helps sperm swim to the egg. After ovulation, mucus becomes thick and sticky again.
A diet rich in whole foods, healthy fats, and complex carbohydrates supports hormonal balance. Include iron-rich foods (leafy greens, lean meat) during your period, and omega-3s (salmon, walnuts) to help reduce inflammation and PMS symptoms.
Regular moderate exercise helps regulate cycles and reduce PMS symptoms. However, excessive intense exercise can disrupt your cycle, especially if combined with calorie restriction. Listen to your body and adjust activity levels throughout your cycle.
Consult a healthcare provider if: your cycles are shorter than 21 days or longer than 35 days, you miss more than 3 periods per year, you have severe pain, bleeding is very heavy (soaking through pads/tampons every hour), or you've been trying to conceive for over 12 months (or 6 months if over 35).
The menstrual cycle is the monthly series of changes a woman's body goes through to prepare for potential pregnancy. Each cycle, one of the ovaries releases an egg (ovulation). Hormonal changes also prepare the uterus for pregnancy. If ovulation occurs but the egg isn't fertilized, the uterine lining sheds through the vagina — this is your period. The average cycle is 28 days, but cycles ranging from 21 to 35 days are considered normal. Your cycle is counted from the first day of your period to the first day of your next period.
Menstruation (Days 1–5): The uterine lining sheds, causing menstrual bleeding. This is day 1 of your cycle. Common symptoms include cramping, fatigue, and bloating.
Follicular Phase (Days 1–13): Overlapping with menstruation, the pituitary gland releases FSH, stimulating follicles in the ovaries to grow. One follicle becomes dominant and prepares to release an egg. Estrogen levels rise, rebuilding the uterine lining.
Ovulation (Day ~14 for 28-day cycle): A surge in LH triggers the release of the mature egg from the ovary. The egg travels down the fallopian tube. This is your most fertile time — the egg can be fertilized for about 12-24 hours.
Luteal Phase (Days 15–28): After ovulation, the ruptured follicle becomes the corpus luteum, producing progesterone to thicken the uterine lining. If pregnancy doesn't occur, the corpus luteum breaks down, hormone levels drop, and the lining sheds as your next period.
Tracking your menstrual cycle helps you understand your body's natural rhythm, predict when your next period will arrive, identify your fertile window if you're trying to conceive, and recognize potential health issues. Irregularities in your cycle can sometimes signal underlying conditions like PCOS, thyroid disorders, or hormonal imbalances. Regular tracking also helps you prepare for period-related symptoms and plan your schedule with confidence.
Our Menstrual Cycle Calculator is designed to help you understand your body's natural rhythm by predicting your next period, ovulation day, and fertile window. Whether you're trying to conceive, tracking your cycle for health awareness, or simply want to be prepared for your next period, this tool provides personalized predictions based on your unique cycle data.
Uses the standard medical formula to predict ovulation and next period dates, based on your cycle length and luteal phase.
See your personalized cycle calendar with color-coded period days, fertile window, and ovulation day for two full cycles.
Adjust cycle length, period length, and luteal phase to match your unique cycle for personalized predictions.
All calculations are performed in your browser. No personal information is stored, transmitted, or shared with any third parties.
Learn about the menstrual cycle phases, ovulation, fertility tracking, and cycle health with our comprehensive guides.
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Medical Disclaimer: This Menstrual Cycle Calculator provides estimates based on standard formulas and should not be used as a primary method of birth control or as medical advice. Cycle tracking accuracy varies based on cycle regularity and individual factors. This tool is for informational and educational purposes only. Always consult with a qualified healthcare provider for fertility, conception, contraceptive, or menstrual health decisions. If you experience severe pain, very heavy bleeding, missed periods, or other concerning symptoms, seek medical attention promptly.