Period Calculator: Menstrual and Ovulation Dates - Clear Calculations (2024)

We created this period calculator to give you a better understanding of when you can expect your period to arrive as well as potential ovulation dates for the next six months based on your cycle.

It also doubles as a fertility calculator with information on your expected most fertile times within the next few months.

Menstrual Cycle Calculator

Results for the Next 6 Months:

Every person with a menstrual cycle knows that it's not always easy to predict when your period will arrive.

Menstrual cycles can vary significantly from person to person, and even within an individual's own cycle. However, having a good understanding of your menstrual cycle and fertility window can be incredibly valuable for various reasons, from family planning to overall health monitoring.

What Is a Menstrual Cycle?

A menstrual cycle is the monthly hormonal cycle that prepares a person's body for potential pregnancy.

The typical cycle is 28 days long, although it can range from 21 to 35 days or more. Many women experience irregular periods which may effect this cycle.

The cycle is divided into several phases, each with its unique hormonal changes and physical symptoms.

Key Phases of the Menstrual Cycle

Menstruation (Days 1-5): The cycle begins with menstruation, the shedding of the lining of the uterus. This is when most people experience their period.

Follicular Phase (Days 1-13): After menstruation, the body begins to prepare for ovulation. Hormone levels, including estrogen, start to rise, stimulating the growth of ovarian follicles.

Ovulation (Around Day 14): Ovulation occurs when a mature egg is released from one of the ovarian follicles. This is the most fertile phase of the cycle and when a woman has the highest chance of getting pregnant.

Luteal Phase (Days 15-28): After ovulation, the body enters the luteal phase. Progesterone levels rise, preparing the uterine lining for potential pregnancy. Symptoms of bloating, mood changes, cramps, and more may begin.

Calculating Your Menstrual Cycle

To calculate your period with the menstrual cycle calculator, you'll need to track a few key pieces of information:

  • First Day of Your Last Period: This is the starting point of your menstrual cycle. It's the first day you notice menstrual bleeding.
  • Duration of Your Period: How long does your average menstrual cycle typically last? Note the number of days you experience menstrual bleeding.
  • Average Length of Cycles: Determine the average number of days between the first day of one period and the first day of the next.

Once you have these details, you can estimate when your next period will arrive. Additionally, knowing the length of your cycle can help you identify your fertile window.

Understanding Your Fertility Window

The fertile window is the timeframe when pregnancy is most likely to occur. It typically spans a few days around the time of ovulation.

If you're trying to conceive, knowing when your fertile window occurs can be crucial.

Here's how to identify it:

  • Ovulation: The fertile window is centered around ovulation, which usually occurs around day 14 of a 28-day cycle. You can track ovulation through methods like tracking basal body temperature, cervical mucus changes, or ovulation predictor kits.
  • Fertile Days: The fertile window includes the day of ovulation and the days leading up to it. Sperm can survive inside the body for several days, so having intercourse in the days before ovulation increases your chances of conception.
  • Fertile Window Variability: Keep in mind that the fertile window can vary from person to person and even from cycle to cycle. Factors like stress, illness, and lifestyle changes can affect the timing of ovulation.

Tracking Your Period: Why It Matters

Being able to predict when your period will start with the period calculator offers numerous benefits that go beyond just knowing when to expect menstrual bleeding.

Here are some compelling reasons why menstrual cycle tracking can be incredibly helpful:

  • Family Planning: For couples looking to start or expand their families, understanding the menstrual cycle is fundamental. Predicting ovulation and the fertile window allows them to maximize their chances of conception.
  • Birth Control: On the flip side, those not yet ready for parenthood can use this knowledge as an essential tool in birth control. By avoiding intercourse during the fertile window, they can reduce the risk of unintended pregnancies.
  • Health Monitoring: Changes in the menstrual cycle can be an indicator of underlying health issues. Irregular periods, for example, can signal hormonal imbalances or conditions like polycystic ovary syndrome (PCOS). Early detection and treatment are vital for maintaining reproductive health.
  • Symptom Management: Knowing when your period is approaching can help you prepare for potential discomfort. You can stock up on necessary supplies, schedule self-care activities, and manage symptoms like cramps and mood swings more effectively.
  • Travel and Lifestyle Planning: Planning vacations, events, or strenuous activities around your menstrual period can make these experiences more comfortable and enjoyable. It allows you to avoid scheduling conflicts with your period.
  • Emotional Well-Being: Anticipating your period can also benefit your emotional well-being. Many people experience mood swings and emotional changes during their cycle. Recognizing these patterns with a period tracker can help you navigate them with greater understanding and self-compassion.

Things to Keep in Mind About Periods

  • Menstrual cycles can vary widely from person to person and even within the same person's cycles. It's perfectly normal for your cycle length, flow, and symptoms to differ over time.
  • While the average length of a menstrual cycle is around 28 days, it's just a guideline. Cycles can range from 21 to 35 days or even more. What's most important is understanding your individual cycle.
  • Period symptoms can differ greatly. Some people may experience mild cramps and little discomfort, while others may have more severe cramps, mood swings, and other symptoms. Your experience is valid, regardless of its intensity.
  • Hormonal changes throughout the cycle can affect your mood, energy levels, and physical well-being. These fluctuations are normal, but they can vary from person to person.
  • Keeping a menstrual calendar or using period calculators like the one above can help you better understand your cycle's patterns. This knowledge can empower you to make informed decisions about your health and lifestyle.
  • If you have concerns about your menstrual cycle, such as irregular periods, severe pain, or heavy bleeding, don't hesitate to seek advice from a healthcare provider. These symptoms could be indicative of underlying health issues that require attention.
  • Your period is a natural part of your reproductive health. Embrace self-care during this time, and remember that it's okay to take it easy when needed. You know your body best, so listen to its cues and prioritize your well-being.
  • Be empathetic and understanding toward others regarding their period experiences. Everyone's journey is unique, and supportive conversations can help reduce stigma and promote open dialogue about menstrual health.


Calculating your menstrual cycle and understanding your fertility window can empower you with knowledge about your reproductive health.

Whether you're trying to conceive or simply want to keep track of your cycles for general health monitoring, this information can be invaluable.

Remember that while tracking your cycle is helpful, it's not a foolproof method of contraception or conception.

For specific family planning needs, consult with a healthcare professional to explore suitable options.

By understanding your body's natural rhythms, you can make informed decisions about your reproductive health and overall well-being.

Period Calculator: Menstrual and Ovulation Dates - Clear Calculations (2024)


When am I most fertile? ›

You ovulate about 12 to 14 days before the start of a new menstrual cycle. Your fertile window is the five days leading up to ovulation, plus the day of ovulation and the day after ovulation — so about seven days in total.

How do I calculate my next period and ovulation date? ›

The length of your menstrual cycle is the number of days from the first day of bleeding in your last period, to the first day of bleeding in your next. From this figure, subtract 14 days from the end of your current cycle to determine the approximate day you ovulate.

How to calculate menstrual cycle and ovulation and safe days? ›

To use the Standard Days method:
  1. Count the days in your menstrual cycle, starting with the first day of your period as day 1. ...
  2. On days 1-7, you're not considered to be fertile and can have unprotected sex, though you may have menstrual bleeding on those days.
  3. On days 8-19, you're considered to be fertile.
Mar 7, 2023

What are the 7 signs of ovulation? ›

What Are the Signs and Symptoms of Ovulation?
  • Changes in Cervical Mucus. Some women experience an increase in cervical mucus, a watery discharge causing dampness, during ovulation. ...
  • Rise in Basal Body Temperature. ...
  • Pelvic Cramping (Mittelschmerz) ...
  • Breast Tenderness. ...
  • Vulval Swelling. ...
  • Backache. ...
  • Perception of Facial Features.
Aug 14, 2023

When are you least likely to get pregnant? ›

The chances of pregnancy are lowest during a person's period and on the days on either side of the period. However, they may still become pregnant if they have ovulated early or late in their cycle, as sperm can survive in the body for several days.

Can you get pregnant when you're not ovulating? ›

Remember, you can get pregnant right after your period, even if you're not yet ovulating. That's because sperm can live up to five days if it's trapped in fertile cervical mucus—so introducing sperm in the days leading up to ovulation can increase your chances of conceiving.

What are the unsafe days to get pregnant? ›

Fertility increases sharply around 12–14 days before menstruation, so unprotected sex is more likely to result in pregnancy during that time. It is unlikely but possible that conception will occur in the 1 or 2 days following a period since sperm can survive for up to 7 days after sex.

How do I know if I am fertile enough to get pregnant? ›

Each month for 6 months, note when your period begins and ends. Then look for your shortest cycle and your longest one during this time. Subtract 18 days from the shortest cycle and 11 days from the longest one. These numbers tell you the time frame when you're most likely to conceive, called your fertile window.

What is the best month to get pregnant? ›

But the most popular time to conceive a baby in the U.S. is November 25 to December 2, per one study published in Human ReproductionOpens a new window. That matches up with Centers for Disease Control (CDC) data suggesting that August and September are among the most popular birth months.

Can men tell when a woman is ovulating? ›

Consequently, that ovulation is “concealed” in women has long been the consensus among scientists studying human mating. A recent series of studies shows, however, that there are discernible cues of fertility in women's social behaviors, body scents, voices, and, possibly, aspects of physical beauty.

Can you feel yourself ovulate? ›

Many people say they feel ovulation pain on just the side that's releasing the egg. This means if the ovary on your right side is releasing the egg, you'll feel pain on your right. Some people find that the pain occurs every month, regardless of which ovary releases an egg.

How do I know if I'm actually ovulating? ›

Changes in basal body temperature, mild cramping and increased sex drive are just a few signs you may be ovulating.

How many days after my period am I fertile? ›

It's difficult to pinpoint exactly when ovulation happens, but in most women it happens around 10 to 16 days before the next period. Women who have a regular, 28-day cycle are likely to be fertile around day 14 of their menstrual cycle, but this won't apply to women whose cycles are shorter or longer.

What are the 4 most fertile days? ›

Ovulation happens about 14 days before your period starts. If your average menstrual cycle is 28 days, you ovulate around day 14, and your most fertile days are days 12, 13 and 14. If your average menstrual cycle is 35 days ovulation happens around day 21 and your most fertile days are days 19,20 and 21.

What is the most fertile age range? ›

A woman's peak reproductive years are between the late teens and late 20s. By age 30, fertility (the ability to get pregnant) starts to decline. This decline happens faster once you reach your mid-30s. By 45, fertility has declined so much that getting pregnant naturally is unlikely.

Can I get pregnant 7 days before my period? ›

Although it is possible to get pregnant in the days leading up to your period, it isn't likely. You can only get pregnant during a narrow window of five to six days a month. When these fertile days actually occur depends on when you ovulate, or release an egg from your ovary.


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