Estimate your fertile window and ovulation day from your last period.
🛠️ Free tool by the NayaPakistan team · Updated September 2026
This calculator estimates your fertile window and likely ovulation day from the first day of your last period and your average cycle length. Ovulation usually happens about 14 days before your next period, and the most fertile days are the five days before ovulation plus the ovulation day itself.
It also shows your estimated next period date. Cycles naturally vary from month to month, so treat these as estimates. This is not a contraceptive method — consult a doctor for family planning or fertility concerns.
Ovulation is estimated about 14 days before your next expected period. Enter your last period date and cycle length and the tool marks the likely ovulation day.
The fertile window is roughly the five days before ovulation plus the day of ovulation — the days when conception is most likely.
No. Cycle-based estimates are not a reliable contraceptive method because ovulation timing varies. Speak to a doctor about proper family-planning options.