You know it takes an egg and a sperm to make a baby—but timing is everything.
If you’ve ever wondered, “When exactly does conception happen?” or “How do I know if I’m ovulating?”, you’re in the right place.
Whether you’re actively trying to conceive or just starting to learn how your body works, understanding ovulation and conception timing can boost your chances—and your confidence.
In this article, we’ll cover:
- What happens during ovulation
- When conception can (and can’t) happen
- How long sperm and eggs survive
- The best days to have sex for pregnancy
Let’s break it down day by day—no guesswork needed.
What Is Ovulation?
Ovulation is when one of your ovaries releases a mature egg. This usually happens once per cycle, about 14 days before your next period—though it varies depending on your cycle length.
Once released, the egg travels down the fallopian tube, where it may meet sperm and become fertilized—that moment = conception.
If the egg isn’t fertilized, your body sheds the uterine lining about two weeks later—your period.
Your Fertile Window: When Can You Get Pregnant?
You can only get pregnant from sex that happens in the 5 days leading up to ovulation—and the day of ovulation itself.
That’s called your fertile window.
| Fertile Window Day | What’s Happening | Pregnancy Potential |
| 5 days before ovulation | Sperm can live in your body, waiting | Possible |
| 3–2 days before | Best chance to conceive | High |
| 1 day before | Peak fertility | Highest |
| Ovulation day | Egg is released | High |
| 1 day after | Egg survives 12–24 hours | Low |
| 2+ days after | No viable egg | Not possible |
Sperm can live up to 5 days, but an egg only survives 12–24 hours. That’s why timing before ovulation is critical.
Day-by-Day Ovulation Breakdown
Let’s map it out assuming a 28-day cycle (adjust accordingly if your cycle is shorter or longer).
- Days 1–7: Menstruation & low fertility
- Days 8–10: Fertile window begins (sperm can survive)
- Days 11–13: Fertile mucus, LH surge — have sex now!
- Day 14: Ovulation = egg released
- Day 15–16: Egg dies if not fertilized
- Days 17–28: Luteal phase—too late for conception
If your cycle isn’t 28 days:
- Subtract 14 from your total cycle length to estimate ovulation day
- Track physical signs (see below) to fine-tune
How to Know When You’re Ovulating
You don’t need to guess. Your body gives you clues.
Cervical Mucus
- Dry/sticky = not fertile
- Creamy = getting closer
- Stretchy, clear, egg-white = ovulation is near
LH Surge (Ovulation Predictor Kits)
- LH spikes ~24–36 hours before ovulation
- Use OPKs daily starting around day 8–10 if unsure.
Basal Body Temperature (BBT)
- Rises 0.3–0.6°C after ovulation
- Confirms that ovulation has occurred (helpful for tracking)
➡️ Read: How to Track Ovulation with Irregular Periods
How Long Do Eggs and Sperm Live?
- Egg lifespan: 12–24 hours after ovulation
- Sperm lifespan: Up to 5 days in cervical mucus
This means the days before ovulation are often more important than the day itself.
Having sex 2–3 days before ovulation often leads to the highest pregnancy rates.
What If You Don’t Know When You’re Ovulating?
No worries—many people don’t at first.
Start with:
- Cycle tracking apps (to estimate)
- OPKs (to detect LH surge)
- Cervical mucus monitoring
- Fertility wearables (like Mira or Oura)
Over 2–3 cycles, you’ll start to see a pattern.
Real-Life Story
“We were only having sex after I got a positive OPK. Turns out, I was ovulating the next day—and missing the window. Once we shifted to 2 days before the test turned positive, I got pregnant in 2 months.”
— Rachel, 35
Myth vs Reality
| Myth | Reality |
| “You can get pregnant any day of your cycle.” | Pregnancy is only possible during your fertile window. |
| “Ovulation always happens on day 14.” | Not always. It varies based on your cycle length. |
| “Sperm dies within a day.” | In fertile mucus, sperm can live for 5 days. |
| “OPKs tell you exactly when to have sex.” | They show a surge, but timing sex before the surge is key. |
Final Thoughts
Conception is about timing, not just luck.
Understanding your fertile window puts the power back in your hands—whether you’re trying now or planning for later.
With a few simple tools and a better understanding of your cycle, you can stop guessing—and start taking control.
Call to Action
👉 Want to know if you’re hitting your fertile window?
Take our 5-minute reproductive health quiz to understand your cycle and fertility profile—and get personalized support.
Sources
- ACOG – Ovulation & Fertility
- Mayo Clinic – Understanding Ovulation
- FertilityIQ – Conception Timing
- NIH – Sperm and Egg Lifespan
Anna Haotanto is the Founder of Zora Health and a passionate advocate for women’s empowerment. Anna’s personal experiences with egg-freezing, PCOS, perimenopause and the challenges of fertility have fueled her mission to provide high-quality information, financing, and support to help women and couples navigate their fertility journeys with confidence. She is also recognised for her achievements in finance, entrepreneurship, and women’s empowerment, and has been featured in various media outlets. You can also follow her on Linkedin or Instagram.
