Ovulation Calculator

This ovulation calculator predicts your ovulation date and fertile window based on the Ogino method. According to this medical theory, ovulation occurs approximately 14 days before the next expected period.

By entering your last menstrual period (LMP) date and average cycle length (typically 21–45 days), the tool calculates your estimated ovulation date and displays your fertile window — from 5 days before ovulation to 1 day after. This calculation is based on medical evidence regarding sperm survival (about 5 days) and egg viability (about 12–24 hours).

Please note that menstrual cycles vary significantly between individuals and can be affected by health conditions, stress, and hormonal changes. Use this calculator as a guide only. For reliable contraception, family planning, or fertility treatment, always consult a qualified healthcare professional such as an obstetrician or gynecologist.