Period Cycle & Ovulation Calculator
Track your menstrual health and predict your most fertile days.
How to Calculate Your Period Cycle Manually
Understanding your menstrual cycle is key to reproductive health, whether you are trying to conceive or simply tracking your wellness. Your cycle length is measured from the first day of one period to the first day of the next.
To calculate your average cycle length, track at least three consecutive months. Add the number of days in each cycle together and divide by three. Most cycles range between 21 and 35 days, with 28 days being the statistical average.
If your last period started on June 1st and your cycle is consistently 28 days long:
– Next Period: June 1 + 28 days = June 29
– Ovulation Day: June 29 – 14 days = June 15
– Fertile Window: June 10 to June 16
Understanding the Phases of Your Cycle
A typical cycle consists of four main phases:
- Menstrual Phase: The days you are bleeding (usually days 1-5).
- Follicular Phase: When your body prepares an egg to be released.
- Ovulation Phase: The mid-point of your cycle where the egg is released. This is the peak time for fertility.
- Luteal Phase: The time between ovulation and your next period. This phase is usually 12-16 days long.
How This Calculator Works
Our tool uses the standard "LMP" (Last Menstrual Period) method combined with your average cycle length. It calculates your next period by adding your cycle length to your last start date. The ovulation date is estimated by subtracting 14 days (the standard luteal phase length) from the projected start date of your next period. The fertile window is the 5-day lead-up to and including the day of ovulation.
Note: This calculator provides estimates based on averages. Hormonal changes, stress, and health conditions can alter your actual cycle. Always consult a healthcare professional for medical advice.