Калькулятор Менструального Цикла и Овуляции

The menstrual cycle and ovulation calculator uses the standard luteal phase model to predict ovulation and fertile windows across 6 future cycles. Ovulation is calculated as cycle length minus 14 days (luteal phase = 14 days), following the Naegele-derived framework used in gynecological practice. For a 28-day cycle this places ovulation on day 14; for a 32-day cycle on day 18.

The fertile window spans 6 days: the 5 days before ovulation (sperm viability window) plus ovulation day itself, when the egg is viable for 12-24 hours post-release. The calculator displays four cycle phases — menstrual, follicular, ovulation, and luteal — with the current phase highlighted based on your last period date. All calculations run locally in your browser; no personal health data is transmitted or stored.

⚕️ Important: This tool provides estimates only. Cycles vary due to stress, illness, body weight, and hormonal conditions like PCOS or perimenopause. It is not a contraceptive method (typical failure rate of fertility awareness methods: 24%/year per CDC). Use alongside our Pregnancy Calculator and consult a gynecologist for fertility planning or irregular cycles.