Knowing the days you are most likely to be fertile can increase your chance of getting pregnant. The typical menstrual cycle is 28 days long, but each woman is different. There are about 6 days during each menstrual cycle when you can get pregnant. This is called your fertile window. Use the calculator to see which days you are most likely to be fertile.
Ovulation Calculator overview
The Ovulation Calculator estimates the most probable ovulation/fertile window as well. The estimations are based on a woman’s last period date. This calculator should not be used as a form of birth control.
Ovulation and Conception
Ovulation in humans is the process by which ovarian follicles rupture and release one or more mature eggs from the ovaries. On average, ovulation occurs within the 4 days before or after the midpoint of a woman’s menstrual cycle (14 days before the start of a woman’s next menstrual period).
Day 10–18 of the menstrual cycle (on average) is the most fertile phase of the menstrual cycle. This is important when trying to conceive because fertilization of the egg can only occur for 12–24 hours after release during part of the luteal phase, when a mature egg travels through the fallopian tubes towards the uterus. Since sperm can survive inside a woman's body for up to five days, regular sex five days before and on the day of ovulation can improve the likelihood of conception. If fertilized, the egg will implant in the uterus 6–12 days later. Otherwise, menstruation occurs, and blood and mucosal tissue from the inner lining of the uterus is expelled.
Many people would like to predict their ovulation date, mostly to increase their chances of getting pregnant. The following are a few common methods for doing so.
Tracking Menstrual Cycles
This ovulation calculator uses the method of tracking menstrual cycles in order to predict when ovulation occurs. Since day 10–18 of the menstrual cycle is typically the most fertile phase of the menstrual cycle, women with regular cycles can fairly easily determine when they are ovulating and most likely to conceive. Menstrual cycles vary between women, however, and a person without a 28-day menstrual cycle may need to track their menstrual cycle to more accurately determine when ovulation might occur.
The first day of the menstrual cycle is the day that bleeding starts, and it ends the day that bleeding starts again. It can be helpful to maintain a menstrual calendar to determine how regular your periods are. If they are irregular, other methods may be more accurate for estimating when ovulation will occur.
Tracking Basal Body Temperatures
Basal body temperature (BBT) is measured using a special thermometer. This is your temperature when you first wake up in the morning. BBT is generally at the lowest level right before ovulation occurs. It starts rising by about ½ a degree a day during ovulation. Tracking BBT over a few months can help you determine when you are ovulating and most likely to be able to conceive. However, there are other factors involved that can affect your BBT, such as having a cold or infection. In these cases, measuring BBT would likely not be a good indicator of ovulation.
It is also possible to use an over-the-counter ovulation test that tests for a surge in some specific hormones that precede ovulation by 24–48 hours. While these tests are 99% accurate in detecting the specific hormones, they cannot guarantee when exactly ovulation will occur within the two-day period. These tests typically measure the level of luteinizing hormone (LH), which, when released in high quantities (and under other conditions), triggers ovulation.
There are also ovulation predictor kits that can test changes in the estrogen level in saliva or salts in the sweat, which change during the month and can be related to the menstrual cycle. These changes generally occur earlier than the hormonal changes (LH increase), and can therefore predict ovulation earlier. Unlike LH tests, this does require more preparation in terms of tracking the levels of these markers to determine a baseline level.
Signs of Ovulation
- Rise in basal body temperature, typically 1/2 to 1 degree, measured by a thermometer
- Higher levels of luteinizing hormone (LH), measured on a home ovulation kit
- Cervical mucus, or vaginal discharge, may appear clearer, thinner, and stretchy, like raw egg whites
- Breast tenderness
- Light spotting
- Slight pain or cramping in your side
- Know when you ovulate:
Ovulation usually happens 14 days before your next period begins, but it can vary from month to month — even in women with regular cycles. To get a better sense of when you’re ovulating, chart your basal body temperature and your cervical mucus. Use an over-the-counter ovulation predictor kit or OPK, ovulation tracking bracelet, or lab tests to check for hormonal changes before ovulation.
- Have sex often:
Your odds of getting pregnant are best when you have sex 1 to 2 days before you ovulate. But cycles vary in length, and some women are irregular or have miscalculated their cycle. Sperm can survive in a woman’s body for up to 5 days. To hedge your bet, have sex frequently starting 3 days before ovulation and continuing for 2 to 3 days after you think you’ve ovulated.
- Lie low after sex?
It has long been believed that you should stay in bed for at least 15 minutes after sex to give sperm a chance to reach the egg. However, recent studies found no evidence to back up this claim.
- Maintain a healthy weight:
Studies show that weighing too little — or too much — may disrupt ovulation and affect production of key hormones. A healthy body mass index is between 18.5 and 24.9. Staying fit with moderate exercise is fine, but this isn’t the time to train for a marathon: Strenuous exercise can mess with your menstrual cycle, making it more difficult for you to conceive.
Research shows that stress may make it harder to get pregnant. Yoga, meditation, and long walks can help lower stress and improve your overall well-being.
- Manage medical conditions.
If you have a medical condition such as diabetes, asthma, or epilepsy, be sure it is under control. Speak with your doctor about any prescription or over-the-counter medications you may be taking, since they might affect your chance of getting pregnant.
- His health matters, too.
While it’s common to think of fertility as the woman’s responsibility, more than 33% of fertility issues involve only the man, and another 33% involve both partners as a couple. Like women, men can improve their reproductive health by quitting smoking, limiting alcohol, eating healthy, and lowering stress.
- Trying for a boy or a girl?
Several theories claim you can influence the gender of your baby by having sex at a certain time of the month or in a specific position. However, there’s no surefire, natural way to choose the sex of your baby. Your odds are 50–50 unless you use a sperm-sorting technique, followed by artificial insemination.
Also, you can try our Period and Ovulation Tracker gadget.