Ovulation timing and signs: when it happens and how long it lasts

Ovulation is the moment an ovary releases an egg, and it's the hinge that pregnancy dating turns on. Understanding when it happens — and the signs that accompany it — makes conception dating and the fertile window far less mysterious.

When does ovulation happen?

On a textbook 28-day cycle, ovulation falls around day 14, roughly two weeks before the next expected period. But cycles vary, and the more reliable landmark is that ovulation tends to occur about 14 days before the next period, regardless of overall cycle length. So on a 32-day cycle, ovulation is nearer day 18. This is exactly why our calculator lets you adjust cycle length — it shifts the dating to match your ovulation timing.

How long does ovulation pain last?

Some people feel a one-sided lower-abdominal twinge around ovulation, sometimes called mittelschmerz. When it occurs, it usually lasts anywhere from a few minutes to a day or two. It's generally mild; pain that is severe, prolonged, or accompanied by other symptoms is worth discussing with a clinician, since it isn't simply ovulation. Not everyone notices ovulation pain at all, and its absence is completely normal.

When is the egg released, and how long does it last?

Once released, the egg survives for about 12 to 24 hours. That's a narrow window, but the fertile window is wider than the egg's lifespan because sperm can survive several days in the reproductive tract. In practice, the fertile window spans roughly the five days before ovulation plus the day of ovulation — intercourse in that span can lead to conception even though the egg itself is short-lived.

Signs of ovulation

Common signals include a change in cervical mucus (becoming clearer and more slippery), a small rise in basal body temperature after ovulation, and, for some, the mid-cycle twinge above. Ovulation predictor kits detect the luteinising hormone (LH) surge that precedes ovulation — useful, though they indicate that ovulation is likely imminent rather than confirming it happened. For how long that surge lasts, see menstrual cycle length and dating.

Why this matters for dating

Because conception happens within about a day of ovulation, knowing your ovulation timing sharpens a due-date estimate — it's the basis of conception dating and of conception mode. If you tracked ovulation this cycle, you can date from it; if not, the last-period method with your real cycle length is the next best thing. To estimate your fertile days for a given cycle, try the ovulation & fertile-window calculator. Either way, an early scan confirms the date.