Ovulation Calculator
Find your fertile window and most likely ovulation date
When Do You Ovulate?
Ovulation typically occurs around 14 days before your next period begins, regardless of how long your cycle is. For a standard 28-day cycle this means ovulation around day 14. For a 32-day cycle it would be around day 18. This calculator adjusts the ovulation date based on your specific cycle length rather than assuming a standard 28-day cycle.
The fertile window spans the 5 days before ovulation plus the day of ovulation itself — a total of 6 days. This is because sperm can survive in the female reproductive tract for up to 5 days, meaning intercourse several days before ovulation can still result in pregnancy. The egg itself is only viable for 12 to 24 hours after ovulation.
Signs of Ovulation
The most reliable physical sign of ovulation is a change in cervical mucus, which becomes clear, slippery, and stretchy — similar to raw egg whites — in the days leading up to ovulation. A slight rise in basal body temperature of 0.2 to 0.5 degrees Celsius typically occurs after ovulation has already happened. Some women also experience mild one-sided pelvic pain called mittelschmerz around ovulation time.
When to Take a Pregnancy Test
After ovulation, if fertilisation has occurred, the fertilised egg takes around 6 to 12 days to implant in the uterine wall. HCG — the hormone detected by pregnancy tests — only begins to rise after implantation. Testing too early produces false negatives. For the most accurate result, wait until the first day of your missed period, which is approximately 14 days after ovulation. This calculator shows you the earliest reliable test date.
Ovulation Calculator — Frequently Asked Questions
When do I ovulate?
For a standard 28-day cycle, ovulation typically occurs around day 14. For cycles of different lengths, ovulation generally happens approximately 14 days before the start of the next period. This calculator estimates your ovulation date based on your cycle length.
What is the fertile window?
The fertile window is the period during which conception is possible. Sperm can survive in the reproductive tract for up to 5 days, so the fertile window spans the 5 days before ovulation plus the day of ovulation itself — a total of 6 days per cycle.
Can I get pregnant outside the fertile window?
Pregnancy is only possible if sperm is present when the egg is released or within 12–24 hours after ovulation. Outside the fertile window the chance of conception is effectively zero, though cycle length can vary making it difficult to predict ovulation precisely without tracking tools.