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Ovulation Calculator

Your menstrual cycle may not always run like clockwork - and that’s perfectly normal. This calculator helps you estimate when you might be ovulating so you can spot your most fertile days. On average, there are about 6 days each month when chances of pregnancy are the most likely - this is known as your fertility window.

How long is your average monthly cycle?

Select the first day of your last period

July 2025

Note: This tool should not be used alone to prevent pregnancy. Results are estimates as ovulation cycles can vary. Consult your doctor for medical advice.

Your Last period:

No. of days:

Fertile Window

July 25 - 30

What is your Fertility Window?

Your fertility window is the set of 6 days in your cycle when your chances of getting pregnant are highest. It usually includes the 5 days before ovulation and the day you ovulate.

Why?

Because sperm can live inside your body for up to 5 days, while an egg survives for only 12–24 hours after release. This means your most fertile time is in the 3 days leading up to and including ovulation day.

Since pinpointing the exact ovulation day can be tricky, having sex every day – or every other day – during this window gives sperm the best chance of meeting the egg.

If you’re trying to avoid pregnancy, you’ll need to be extra careful during this window by either avoiding sex or using contraception. But remember – no method of tracking ovulation is 100% foolproof, so pregnancy can sometimes happen outside this window too.

Approximate Ovulation

July 25 - 30

Handy Mnemonic – “B.M.C.S.”

Bloating • Mucus changes • Cramps • Sore breasts

What Is Ovulation?

Ovulation is the point in your cycle when one of your ovaries releases an egg. The timing depends on how long your menstrual cycle is, but it usually occurs about 14 days before your next period. For example, if you have a 28-day cycle, you’ll likely ovulate around day 14 after your period begins.

Your ovulation day can shift slightly from month to month. Hormonal birth control (like the pill) works by stopping ovulation altogether. Other factors that may delay or prevent ovulation include:

Very high or very low body fat
Intense or excessive exercise
Extreme stress or fatigue
Breastfeeding
Certain medical conditions such as PCOS or primary ovarian failure

Once an egg is released, it survives only 12–24 hours. If you’re trying to conceive, plan intercourse in the 3 days leading up to ovulation, so sperm are ready and waiting. If you’d rather avoid pregnancy, use contraception or abstain during those fertile days.

If the egg isn’t fertilized, your period will arrive about two weeks later. If fertilization occurs, the egg travels to the uterus for implantation. During implantation, you might notice:

Light spotting that’s brown or pink (not bright red)
Mild cramps that feel gentler than period pain

Next Period

July 25 - 30

Understanding Your Menstrual Cycle

Your menstrual cycle begins on the first day of bleeding (menstruation) and ends the day before your next period starts. The length can vary from month to month — anywhere between 15 and 50 days.

The cycle has two main phases:

Follicular Phase

This phase starts with your period, when the lining of your uterus (built up to nourish a fertilized egg) is shed through your vagina. Hormones then signal your ovaries to prepare a new egg, and your uterine lining begins to rebuild. The follicular phase ends once ovulation occurs.

Luteal Phase

After ovulation, the uterine lining continues to thicken, and your breasts may feel tender as your body prepares for a possible pregnancy. If conception doesn’t happen, hormone levels drop, and your next period begins.

While the luteal phase is usually consistent, the follicular phase can vary widely, which makes predicting ovulation with a calendar alone tricky. And though it’s uncommon, pregnancy during your period is still possible.

If you’re under 35 and trying to conceive, your chances of getting pregnant in any given cycle are roughly 1 in 4.

Visual Representation of the Menstrual Cycle

Menstruation

If you’re not pregnant, the lining of your uterus (endometrium) sheds through the vagina, lasting about 3–7 days.

Follicular Phase

During this phase, hormones signal the ovaries to prepare follicles containing eggs, while your uterine lining begins to thicken again.

Ovulation

Around the middle of your cycle, an ovary releases an egg. The egg survives for up to 24 hours, and this is the time when conception is most likely.

Luteal Phase

After ovulation, the uterine lining grows thicker to support a possible pregnancy. If sperm fertilizes the egg and it implants in the lining, pregnancy begins. If not, the lining eventually sheds with your next period.

Pregnancy Test Day

July 25 - 30

Pregnancy Testing

Can’t wait to know if you’re pregnant? Some extra-sensitive home tests can show a result a few days before your period is due. For the most reliable answer, test the day after your expected period.

Pregnancy tests check for a hormone called hCG (human chorionic gonadotropin), which your body starts making once a fertilized egg implants in your uterus. By the time you’ve missed a period, hCG levels are usually high enough to detect.

You can take a urine test at home or a blood test at your doctor’s clinic. Used correctly, home tests are almost 99% accurate. A false positive is rare, but it may happen if you’re taking medication with hCG. False negatives are more common if:

You tested too early (perhaps you ovulated later than expected).
Directions weren’t followed precisely — for example, using too much or too little urine.

Remember, sperm can live up to 5 days inside your body, while an egg survives only 12–24 hours. Timing can affect when hCG shows up.

If you’re at-home test is positive, see your doctor to confirm and start prenatal care. If it’s negative but your period doesn’t arrive, wait a couple of days and test again.

Earliest Signs of Pregnancy

Some women notice changes just days after conception, but only a test can confirm pregnancy. Common early signs include:

Headaches – Hormonal shifts or dehydration from nausea may trigger them.
Changes in taste – Sudden food aversions or strong cravings can appear.
Tiredness – Higher progesterone levels may leave you feeling unusually sleepy.
Nausea (“morning sickness”) – Can happen any time of day.
Frequent urination – More blood flow means your kidneys work harder.
Tender breasts – Hormonal changes can make them sore or swollen.
Higher body temperature – If your basal temperature stays up after ovulation, it could be an early sign.

Estimated Due Date

July 25 - 30

Calculating Your Due Date

To estimate when your baby might arrive, count 40 weeks (about 280 days) from the first day of your last menstrual period. That’s the average length of pregnancy.

Remember, this is only an estimate, most babies don’t arrive exactly on their due date. This calculation also assumes you have a regular menstrual cycle.

July 2025

Ovulation Calculator

How long is your average monthly cycle?

Select the first day of your last period

Fertile Window

What is your Fertility Window?

Why?

Approximate Ovulation

Handy Mnemonic – “B.M.C.S.”

What Is Ovulation?

Next Period

Understanding Your Menstrual Cycle

The cycle has two main phases:

Follicular Phase

Luteal Phase

Menstruation

Follicular Phase

Ovulation

Luteal Phase

Pregnancy Test Day

Pregnancy Testing

Earliest Signs of Pregnancy

Estimated Due Date

Calculating Your Due Date

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