When do I ovulate?
Ovulation is the release of an egg from an ovary, once in each menstrual cycle. It usually happens about 14 days before the next period begins, so in a 28-day cycle it falls around day 14 and in a 32-day cycle around day 18. The days before ovulation are the most fertile, because sperm can wait up to five days for the egg.
Example: a period that began on March 1, 2027, with a 28-day cycle, means ovulation around March 15 and a fertile window from March 10 to 16. The next period is due on March 29.
Signs of ovulation
- Clear, stretchy cervical mucus, like raw egg white.
- A small rise in basal body temperature, about 0.5 °F (0.3 °C), the day after ovulation.
- A positive ovulation test (LH surge) 24 to 36 hours before ovulation.
- Mild pain on one side of the lower abdomen for some people.
The luteal phase
The part of the cycle after ovulation, the luteal phase, is fairly steady at 12 to 14 days, while the part before it varies. That is why ovulation is counted back from the next period, not forward from the last one. If you track your temperature and know your luteal phase, enter it for a more precise date.
Frequently asked questions
How accurate is an ovulation calculator?
It works best with regular cycles. Stress, illness and travel can shift ovulation by a few days, so ovulation tests are useful to confirm it.
When should I take a pregnancy test?
From the first day of a missed period. Home tests can sometimes detect pregnancy a few days earlier, but a negative result then is less reliable.
Can I use this as birth control?
No. Calendar estimates are not reliable enough to prevent pregnancy, because ovulation can come earlier or later than expected.