Ovulation calculator.
Enter the first day of your last period and your average cycle length. Get your estimated ovulation day, your fertile window, and the same dates projected forward for the next six cycles. Calibration only - not a substitute for monitored cycles.
How this calculator works
Ovulation is estimated as 14 days before the start of your next period. Your fertile window is the 5 days before ovulation plus the day of ovulation - sperm survives in the female reproductive tract for up to 5 days, while an egg is viable for about 12-24 hours.
This calculation assumes regular cycles. If your cycles are irregular, vary by more than 7 days, or you have polycystic ovary syndrome (PCOS), this calculator will be less accurate. In that case, ovulation predictor kits or ultrasound monitoring give better data.
What this does not tell you
Whether you will get pregnant in any given cycle. Whether you are ovulating at all. Whether your partner's sperm is reaching the egg. None of those questions can be answered by a calendar calculation.
If you have been trying for 12 months without success (or 6 months if you are 35 or older), it is worth a fertility evaluation regardless of what this calculator shows.
For a personalised plan
If your cycles are irregular or you have been trying for over a year, our partner property handles consultations.
Book a remote consult on ikivana.com →