Pregnancy Due Date Calculator

Use our pregnancy due date calculator to estimate your baby’s due date and see how many weeks pregnant you are. Please note this tool is for information purposes only. Your due date should always be confirmed by your healthcare provider or ultrasound scan.

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Due Date Calculator

When did your last period start?

Generally, how long are your cycles?

Calculate your due date

Your baby is likely to be born on or around*

*Only your physician can accurately determine your due date or the date of your conception based on his/her knowledge of your complete medical condition.

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In partnership with Clearblue®.

Discover More About Our NIPT Offering

We work with a number of partner clinics and hospitals around Ireland

Panorama Test (9 Weeks)

Harmony Test (10 Weeks)

PrenatalSEQ Test (10 Weeks)

How Is a Pregnancy Due Date Calculated?

A pregnancy due date is usually calculated based on a 40-week pregnancy, starting from the first day of your last menstrual period (LMP). This method assumes a regular menstrual cycle and ovulation occurring around the middle of the cycle.

Because every pregnancy is different, your estimated due date may be adjusted following an early ultrasound scan, which is considered the most accurate way to confirm gestational age.

How Accurate Is a Due Date Calculator?

A due date calculator provides an estimate rather than a guaranteed delivery date. Only around 5% of babies are born on their exact due date.

Early ultrasound dating is the most accurate method for confirming gestational age, particularly in the first trimester. If there is a difference between your calculated due date and scan results, your healthcare provider will advise which date to follow.

Pregnancy Weeks & Key Milestones

Knowing how many weeks pregnant you are can help you understand key stages of pregnancy, including trimester changes and when certain screening tests may be offered.

Pregnancy is typically divided into three trimesters:

First trimester: Weeks 1–12
Second trimester: Weeks 13–27
Third trimester: Weeks 28–40

When Can I Have an NIPT Test?

Non-invasive prenatal testing (NIPT) is typically available from 10 weeks of pregnancy with Harmony & PrenatalSEQ tests or as early as 9 weeks of pregnancy with the Panorama test.

Understanding your gestational age can help determine when prenatal screening tests may be appropriate. NIPT is a screening test and should always be discussed with your healthcare provider or referring clinician.

More about NIPT

YOUR QUESTIONS, ANSWERED WITH CAREFrequently Asked Questions

Common questions about pregnancy due dates for expectant parents.

How is my pregnancy due date calculated?

Your due date is estimated based on the first day of your last menstrual period and a standard 40-week pregnancy timeline.

Can my due date change after an ultrasound?

Yes. Early ultrasound scans are considered the most accurate method of pregnancy dating and may adjust your estimated due date.

How many weeks pregnant am I?

This calculator estimates how many weeks pregnant you are based on the date entered. Your healthcare provider can confirm this through ultrasound.

Is this calculator accurate for IVF pregnancies?

This calculator is designed for natural conception based on LMP. IVF pregnancies are typically dated using embryo transfer information and should be discussed with your fertility clinic.

This pregnancy due date calculator is provided for information purposes only and does not replace medical advice. Always consult your healthcare provider for confirmation of gestational age and pregnancy care.

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