SnapCalc

Pregnancy Due Date Calculator

Calculate your estimated due date, current week of pregnancy, and key milestone dates.

Enter the relevant date based on your selected method

Only used for LMP method — default is 28 days

How to Use This Calculator

1. Choose your calculation method:

  • LMP — most common; enter the first day of your last period
  • Conception date — if you know when conception occurred
  • IVF transfer — for day-5 embryo transfers
    • 2. Enter your date 3. For LMP — enter your average cycle length if it differs from 28 days 4. Click Calculate to see your due date and milestones

    Important Note:

    This calculator provides an *estimate*. Due dates are typically accurate within ±2 weeks. Your doctor or midwife will confirm with an ultrasound.

    Formula

    Naegele's Rule: Due Date = LMP + 280 days (adjusted for cycle length)

    Frequently Asked Questions

    How accurate is an estimated due date?

    Only about 5% of babies are born on their exact due date. Most are born within 2 weeks either side. Early ultrasound (before 14 weeks) gives the most accurate estimate.

    What is full term?

    Full term is 39–40 weeks. "Early term" is 37–38 weeks. Babies born at 37 weeks are considered viable but may have more challenges than those born at 39+ weeks.

    What if my cycle is not 28 days?

    This calculator adjusts for non-standard cycles. If your cycle is 35 days, conception typically occurs around day 21 rather than day 14, shifting your due date later.

    When is the first trimester over?

    The first trimester ends at 13 weeks and 6 days. The second trimester runs from week 14 to 27. The third trimester is week 28 until birth.

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