Ovulation itself lasts only about one day. The egg your ovary releases survives for less than 24 hours, so the actual window where fertilization can happen is remarkably short. But because sperm can live inside the reproductive tract for up to five days, your total fertile window stretches to roughly six days: the five days before ovulation plus the day of ovulation itself.
That distinction matters. Most people searching this question want to know either how long they can get pregnant or how to time intercourse. The answer depends on understanding both the egg’s brief lifespan and the longer survival time of sperm.
Why Ovulation Lasts Only One Day
Each menstrual cycle, one ovary releases a single mature egg. Once that egg leaves the ovary, it travels into the fallopian tube, where it remains viable for fertilization for fewer than 24 hours. If sperm don’t reach and penetrate the egg within that narrow window, the egg breaks down and is absorbed by the body. This is ovulation in the strictest sense: a single event that plays out over the course of one day.
Your body doesn’t release eggs over multiple days. Even in cycles where you feel symptoms for two or three days (bloating, mild pelvic pain, breast tenderness), the egg release is a one-time moment. Those lingering symptoms reflect the hormonal shifts surrounding ovulation, not ongoing egg release.
Your Six-Day Fertile Window
Sperm are far hardier than the egg. Under the right conditions, sperm deposited in the reproductive tract can survive for up to five days, waiting in the fallopian tubes for an egg to arrive. This means intercourse that happens several days before you ovulate can still result in pregnancy. The most fertile days are typically the two to three days leading up to ovulation and the day of ovulation itself.
After ovulation, the window closes quickly. Because the egg lives less than 24 hours and sperm need time to travel, the day after ovulation is generally too late for conception. This is why timing matters more on the front end of the fertile window than the back end.
When Ovulation Happens in Your Cycle
A common rule of thumb places ovulation around day 14 of a 28-day cycle, but this is a rough average, not a reliable predictor. The first half of your cycle (from the start of your period to ovulation) is called the follicular phase, and its length varies significantly from person to person and even cycle to cycle in the same person. The majority of variation in overall cycle length comes from this phase.
The second half of the cycle, after ovulation, is more predictable. This phase typically lasts between 10 and 15 days and stays relatively consistent for each individual. So if your cycle is 32 days long, you likely ovulate around day 17 or 18, not day 14. If your cycles are irregular, ovulation timing can shift substantially from one month to the next.
A practical way to estimate: count backward about two weeks from the expected start of your next period. That gives you a better approximation than counting forward from your last period.
How to Spot Ovulation
Cervical Mucus Changes
Your body gives visible signals as ovulation approaches. Cervical mucus follows a predictable pattern across the cycle. After your period, discharge is typically dry or tacky. Over the following days, it becomes sticky and white, then creamy and cloudy. In the days right before ovulation, it shifts to a clear, stretchy consistency that resembles raw egg whites. This slippery, wet mucus appears for about three to four days and signals your most fertile time. After ovulation, mucus dries up again and stays that way until your next period.
Rising estrogen levels drive this change. The egg-white mucus creates an environment that helps sperm survive and travel more easily. If you notice this texture, you’re likely in your fertile window.
Ovulation Predictor Kits
Home ovulation predictor kits (OPKs) detect a surge in luteinizing hormone (LH) in your urine. This surge happens roughly 24 to 48 hours before ovulation, giving you a short heads-up that the egg is about to be released. Ovulation typically occurs between 8 and 20 hours after LH reaches its peak.
These kits are reliable. A 2024 study in Fertility and Sterility compared five popular brands and found surge detection accuracy ranged from about 92% to 97% when compared against blood LH levels. Price didn’t make a meaningful difference in accuracy. Sensitivity (how well the kit catches the surge when it’s actually happening) varied more, ranging from about 38% to 77% depending on the brand, so testing at consistent times each day improves your odds of catching the surge.
A positive test means ovulation is likely within 12 to 48 hours. The best time to have intercourse for conception is the day of a positive OPK and the following day.
Putting the Timing Together
Here’s how these pieces fit in practice. If you have a 28-day cycle, your fertile cervical mucus typically appears around days 10 to 14. An OPK would likely turn positive around day 12 or 13, and ovulation would follow within a day or two. The egg then survives for less than 24 hours.
For someone with a 35-day cycle, all of these markers shift later, perhaps to days 19 through 21. The fertile window and ovulation signs stay the same in duration and character. They just occur at a different point in the cycle.
If you’re tracking for pregnancy, combining methods gives the clearest picture. Monitoring cervical mucus gives you an early warning that fertility is ramping up, while an OPK confirms the surge is underway. If you’re tracking to avoid pregnancy, keep in mind that these methods identify the fertile window but don’t guarantee its boundaries, especially in irregular cycles.