myOvulation Calculator
Find your fertile window and estimated ovulation date based on your cycle.
This calculator provides estimates based on average cycle patterns. Individual cycles vary. For medical advice or fertility treatment, consult a healthcare professional.
About the Ovulation Calculator
Ovulation is the release of a mature egg from the ovary, typically occurring once per menstrual cycle. This calculator estimates your ovulation date and fertile window using the standard formula: ovulation occurs approximately 14 days before your next period (or more precisely, cycle length minus luteal phase length).
How ovulation is estimated
The calculation uses two key inputs — your last menstrual period (LMP) date and your average cycle length — to project when ovulation is likely to occur in your current cycle:
- Ovulation day — cycle length minus luteal phase length (default 14 days)
- Fertile window — 5 days before ovulation through the day of ovulation (6 days total)
- Next period — LMP date plus average cycle length
Phases of the menstrual cycle
The menstrual cycle has four phases. The menstrual phase (days 1–5) is when the uterine lining sheds. The follicular phase (days 1–13) overlaps with menstruation and continues until ovulation as an egg matures. The ovulatory phase (around day 14) is the brief window when the egg is released. The luteal phase (days 15–28) follows ovulation as the body prepares for potential implantation.
Signs of ovulation
Common physical signs include a change in cervical mucus (becoming clear and stretchy, like raw egg white), a slight rise in basal body temperature (about 0.2°C) after ovulation, and mild one-sided pelvic pain (mittelschmerz). Ovulation predictor kits (OPKs) detect the LH surge that precedes ovulation by 24–36 hours and are the most reliable at-home method for pinpointing ovulation.