Know Your Most Fertile Days
Women who track their ovulation and fertile days increase their chances of conceiving during each cycle. Many online tools fail to provide accurate results, but our fertility calculator offers a precise estimate of your fertile window. It also helps detect early pregnancy.

Boost Your Chances of Pregnancy
To increase the chances of getting pregnant, the key is knowing when ovulation occurs and identifying fertile days. Ovulation timing is the most important detail to focus on, along with confirming that the male partner has a healthy sperm count. Pregnancy can happen only during the 4–5 days leading up to ovulation and on the day ovulation occurs. Tracking ovulation helps couples plan intercourse for the best timing.

What Triggers Ovulation?
As ovulation approaches, the body experiences hormonal changes. Follicle-stimulating hormone (FSH) supports egg development, preparing it for release. Luteinizing hormone (LH) then signals the ovaries to release the egg by increasing estrogen levels. As estrogen rises, it thickens the uterine lining to prepare for pregnancy and thins cervical mucus, helping sperm reach the egg. A sudden surge in LH forces the follicle to release the egg into the fallopian tube, marking ovulation. This process repeats each month unless the egg implants or menstruation begins.

How Reliable Is This Ovulation Calculator?
Our ovulation calculator, created by an experienced OB-GYN with over 30 years in practice, accurately predicts fertile days and ovulation timing. It also calculates when implantation might happen, when pregnancy signs may appear, and the earliest date for a positive pregnancy test. Additionally, it identifies less fertile days to help couples understand when pregnancy is unlikely.

Using the Fertility Calendar
To use the fertility calculator, enter the first day of your last period and the average length of your menstrual cycle (usually 28–29 days). If you are unsure about cycle length, the default values can be used. Tracking cycles over time improves accuracy and helps predict ovulation more effectively.

Fertile Days vs. Fertility Window
The fertility window spans 5–6 days when pregnancy is most likely to occur. These include the 5 days before ovulation and the day of ovulation. Fertile days can extend beyond this window, covering any time during the cycle when conception is possible due to variations in ovulation timing. Unlike the fertility window, fertile days provide a broader range to improve flexibility for planning intercourse.

Can Pregnancy Happen After Ovulation?
Getting pregnant after ovulation is unlikely since an egg survives for only 12–24 hours. Sperm must already be present in the reproductive system during ovulation to fertilize the egg. However, sperm can live up to 6 days in the body, allowing conception if intercourse occurs within that timeframe before ovulation.

Does Ovulation Always Occur on the Same Day?
Even with regular cycles, ovulation can shift slightly each month. Waiting to have sex until after a temperature rise or a positive ovulation test may miss the fertile window, as ovulation may have already passed. For the best chances, aim to have intercourse once a day or every other day during the 4–5 days leading up to ovulation and on ovulation day.

Intercourse Timing and Pregnancy Chances:

• Daily sex: 37% chance of pregnancy
• Every other day: 33% chance of pregnancy
• Once a week: 15% chance of pregnancy

Couples with sperm concerns may follow the every-other-day rule to allow recovery time for sperm production. Consistent planning and tracking help improve the likelihood of conception.