Ovulation Calculator Sri Lanka | Estimate Ovulation Date

This ovulation calculator helps estimate the day you may ovulate based on the first day of your last period and your average cycle length. It can be useful when planning pregnancy, but it is only an estimate.

First day of last menstrual period

Average cycle length (days)

Most cycles are 28 days. Usual range is 21–45 days.

Your cycle length is outside the usual range for this calculator. Please consult a healthcare professional if your cycles are very irregular.

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Your Ovulation Estimate

Based on your last period and cycle length

Estimated ovulation date

Most fertile days

Estimated fertile window

Next expected period

ℹ️ This is an estimate, not a diagnosis Ovulation can vary from cycle to cycle due to stress, illness, hormonal changes, irregular periods, breastfeeding, age, and medical conditions. This tool should not be used as a guaranteed method to achieve or avoid pregnancy.

How Does This Ovulation Calculator Work?

This calculator uses a standard formula. Your estimated ovulation date is calculated as your cycle length minus 14 days from the start of your next expected period. The fertile window spans approximately 5 days before ovulation and one day after.

What Is Ovulation?

Ovulation is the release of an egg from an ovary. It usually occurs once per cycle, around 14 days before the next period. The egg survives for about 12–24 hours. Sperm can survive in the reproductive tract for up to about 5 days.

Accuracy Limitations

Calendar-based estimates assume a regular cycle. Many factors can shift ovulation earlier or later, including stress, illness, significant weight change, breastfeeding, polycystic ovary syndrome (PCOS), thyroid conditions, and approaching menopause.

When Should You See a Doctor?

Seek medical advice if your cycles are very irregular, periods stop unexpectedly, bleeding is very heavy, you have severe pain, or you have difficulty conceiving after trying for a reasonable period.

Related Fertility Tools

Frequently Asked Questions

It gives an estimate only. Ovulation can change from cycle to cycle, especially with irregular periods, illness, stress, breastfeeding, hormonal conditions, or age-related changes.

No. This calculator should not be used as a guaranteed method to avoid pregnancy.

The fertile window is the group of days when pregnancy is more likely. It usually includes the days before ovulation and the day of ovulation.

Seek medical advice if your cycles are very irregular, periods stop unexpectedly, bleeding is very heavy, you have severe pain, or you have difficulty conceiving after trying for a reasonable period.

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Educational Tool — Not Medical Advice

This calculator gives an estimate based on cycle dates. Ovulation can vary from cycle to cycle due to stress, illness, hormonal changes, irregular periods, breastfeeding, age, and medical conditions. This tool is not a diagnostic test and should not be used as a guaranteed method to achieve or avoid pregnancy.