Calculate your ovulation date, fertile window, and next period date from your cycle details. Color-coded calendar with 3-cycle preview.
This method works best for regular cycles of 26–32 days. Use OPKs or BBT tracking for more precision.
You are most fertile during the 5 days before ovulation, the day of ovulation, and 1 day after — a 7-day window. Ovulation typically occurs 14 days before your next expected period.
Signs include clear egg-white cervical mucus, mild pelvic cramping (mittelschmerz), a slight rise in basal body temperature, and increased libido. Ovulation predictor kits (OPKs) detect the LH surge 24–36 hours before ovulation.
The chances are very low but not zero. Sperm can survive up to 5 days. The egg survives 12–24 hours after release. Outside this window, conception is biologically unlikely but irregular ovulation makes timing uncertain.
This calculator assumes a regular cycle. Irregular cycles (from stress, PCOS, thyroid issues, etc.) make calendar-based prediction less reliable. Use basal body temperature tracking or OPKs for more accuracy. Consult a gynaecologist if cycles are consistently irregular.
The calendar method is 76–88% effective with perfect use, and less effective with typical use. It works best for women with regular cycles of 26–32 days. Do not rely on it as the sole contraceptive without understanding its limitations.