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10/19/2026 1:48 p.m.

What Are Your Chances of Getting Pregnant During Your Fertile Window?

Sonja Windhager Health Writer

On your most fertile day, the chance of getting pregnant from a single act of intercourse is about one in three. At the start of your fertile window, it's about one in ten.1 Over several cycles, it adds up. What matters most is knowing your fertile days.

At a glance

  • Your fertile window lasts six days: the five days before ovulation and ovulation day.1
  • The chance per day ranges from about 10% to about 33%.1
  • With well-timed intercourse, about 80% of couples are pregnant after six cycles.3
  • Sex every one to two days during your fertile window is enough.2

What are your chances per day?

Your chance per day ranges from about 10% five days before ovulation to about 33% on ovulation day.1

You can only get pregnant on six days of your cycle, because sperm survive up to five days but the egg only a few hours.1 The closer to ovulation, the higher the chance.

You may have read "10% at most." That number comes from counting by cycle day without knowing when ovulation occurs.2 If you know when you ovulate, you can focus on the days with the highest chance.

What are your chances per cycle?

Among couples who timed sex to their fertile days, almost 4 in 10 got pregnant in the first cycle, and the chance adds up over time.3

Among couples who timed intercourse to their fertile days, 38% were pregnant in the first cycle, 81% after six and 92% after twelve cycles.3 Without targeted cycle observation, the literature gives about 60% after six and 85% after twelve months.4

How often should you have sex to get pregnant?

Every one to two days during your fertile window.2

Daily sex isn't necessary, but more frequent sex doesn't lower your chances either.2 Timing matters more: the best days are the two to three days before ovulation and ovulation day.1

How does Daysy help you find your fertile days?

Daysy shows your fertile window in red so you can make the most of the days with the highest chance.

Daysy measures your basal body temperature every morning, learns your individual cycle, and detects from the temperature rise whether and when you ovulated. Even a day with about a 10% chance is a fertile day, which is why Daysy shows it in red. In an analysis of 107,020 cycles, Daysy identified the non-fertile (green) days with 99.4% accuracy.5

Why Doesn't Daysy Need Cervical Mucus?

When should you see a doctor?

If you're not pregnant after 12 months, or after six months if you're 35 or older.2 It makes sense to go sooner if your periods are very irregular or stop. You can bring your cycle data from the DaysyDay app to your appointment.

FAQ

How many days a month can you get pregnant?

Six days: the five days before ovulation and ovulation day.
How long does it usually take to get pregnant?

With well-timed intercourse, about 80% of couples are pregnant after six cycles, and over 90% after twelve.
When should I see a doctor if I'm not getting pregnant?

After 12 months without a pregnancy, or after six months if you're 35 or older.

Sources

1)
Wilcox, A. J.; Weinberg, C. R.; Baird, D. D. Timing of sexual intercourse in relation to ovulation. Effects on the probability of conception, survival of the pregnancy, and sex of the baby. The New England Journal of Medicine. 333(23), 1517–1521 (1995).
DOI: 10.1056/NEJM199512073332301. Available at: doi.org .
2)
Practice Committee of the American Society for Reproductive Medicine. Optimizing natural fertility: a committee opinion. Fertility and Sterility. 117(1), 53–63 (2022).
DOI: 10.1016/j.fertnstert.2021.10.007. Available at: doi.org .
3)
Gnoth, C.; Godehardt, D.; Godehardt, E.; Frank-Herrmann, P.; Freundl, G. Time to pregnancy: results of the German prospective study and impact on the management of infertility. Human Reproduction. 18(9), 1959–1966 (2003).
DOI: 10.1093/humrep/deg366. Available at: doi.org .
4)
Raith-Paula, E.; Frank-Herrmann, P.; Freundl, G.; Strowitzki, T. Natürliche Familienplanung heute [Natural family planning today; in German]. Springer. 4th ed, 152 (2008).
5)
van de Roemer, N.; Haile, L.; Koch, M. The performance of a fertility tracking device. The European Journal of Contraception & Reproductive Health Care. 26(2), 111–118 (2021).
DOI: 10.1080/13625187.2021.1871599. Available at: doi.org .

Reviewed by

Natalie Rechberg

Founder of Daysy | CEO of Valley Electronics AG

Natalie Rechberg is the founder of Daysy and CEO of Valley Electronics AG. She is committed to helping women better understand their cycle. Her focus areas are FemTech, cycle health, and cycle tracking. Her goal: to make clear, accessible knowledge about the menstrual cycle available to women and to combine modern technology with sound knowledge of the female body.

Areas of expertise
FemTech, cycle health, cycle tracking
Updated
October 19, 2026
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