How many weeks is a full-term pregnancy?

A full-term pregnancy is 40 weeks (280 days) counted from the first day of the last menstrual period, or 38 weeks from actual fertilization/conception.

What are the trimester date ranges?

First Trimester: Week 1 to Week 13; Second Trimester: Week 14 to Week 27; Third Trimester: Week 28 to Week 40+.

What percentage of babies are born exactly on their due date?

Only about 4% to 5% of babies are born on their exact calculated due date. Most full-term births occur within a 2-week window (between 37 and 42 weeks).

How does an ultrasound scan date compare to LMP calculation?

First-trimester crown-rump length (CRL) ultrasound measurements are highly accurate and often adjust the clinical due date if discrepancy with LMP exceeds 5–7 days.

How does IVF transfer date determine due date?

For a 3-day embryo transfer: Due Date = Transfer Date + 263 days. For a 5-day blastocyst transfer: Due Date = Transfer Date + 261 days.

Health & Fitness Cluster

Pregnancy Due Date Calculator (Estimated Due Date & Trimester Timeline)

Calculate your estimated delivery date (EDD), current pregnancy week, and trimester timeline.

TL;DR: Pregnancy Due Date Calculator estimates your delivery date using Naegele's Rule (LMP + 280 days), tracking gestational age and key fetal milestones.

First day of last menstrual period

How Is a Pregnancy Due Date Calculated Using Naegele's Rule?

Naegele's Rule calculates estimated due date (EDD) by adding 1 year, subtracting 3 months, and adding 7 days to the first day of your Last Menstrual Period (LMP) (equivalent to LMP + 280 days / 40 weeks). If conception date is known, due date is Conception Date + 266 days (38 weeks).

How to Use the Pregnancy Due Date Calculator

Our Pregnancy Due Date Calculator performs high-precision mathematical operations directly in your browser with zero latency and complete client-side privacy.

Select calculation method: Last Menstrual Period (LMP), Conception Date, or IVF Transfer Date.
Enter the date corresponding to your selected method.
Input your average menstrual cycle length (default is 28 days).
Click 'Calculate Due Date' to view Estimated Delivery Date (EDD).
Review current gestational week/day and trimester milestone timeline.

Mathematical Formula & Equations

Estimates expected date of delivery (EDD) and current gestational age in weeks and days based on standard 280-day gestation.

\[ \text{Naegele's Rule: } \text{Due Date} = \text{First Day of Last Menstrual Period (LMP)} + 1 \text{ Year} - 3 \text{ Months} + 7 \text{ Days} \]

Calculation Example

LMP on May 10, 2025 gives an estimated due date of February 17, 2026.

100% Client-Side Privacy & Data Security

All calculations, amortization schedules, variables, and sensitive numerical datasets execute 100% locally in your web browser memory. Your financial, medical, and personal values are never transmitted, logged, or uploaded to any external server.

Frequently Asked Questions

: A full-term pregnancy is 40 weeks (280 days) counted from the first day of the last menstrual period, or 38 weeks from actual fertilization/conception.
: First Trimester: Week 1 to Week 13; Second Trimester: Week 14 to Week 27; Third Trimester: Week 28 to Week 40+.
: Only about 4% to 5% of babies are born on their exact calculated due date. Most full-term births occur within a 2-week window (between 37 and 42 weeks).
: First-trimester crown-rump length (CRL) ultrasound measurements are highly accurate and often adjust the clinical due date if discrepancy with LMP exceeds 5–7 days.
: For a 3-day embryo transfer: Due Date = Transfer Date + 263 days. For a 5-day blastocyst transfer: Due Date = Transfer Date + 261 days.

Cite This Calculator

Need to reference this online calculator in a financial proposal, academic paper, blog post, or classroom curriculum? Copy a citation below.

NexLove.org. (2026). Pregnancy Due Date Calculator [Online Calculation Tool]. https://nexlove.org/tools/pregnancy-due-date-calculator

“Pregnancy Due Date Calculator.” NexLove.org, 2026, nexlove.org/tools/pregnancy-due-date-calculator.

NexLove.org (2026) Pregnancy Due Date Calculator. Available at: https://nexlove.org/tools/pregnancy-due-date-calculator (Accessed: 2026).

@misc{nexlove_pregnancy_due_date_calculator,
  title = {Pregnancy Due Date Calculator},
  author = {{NexLove.org}},
  year = {2026},
  url = {https://nexlove.org/tools/pregnancy-due-date-calculator}
}

Embed This Tool

Add the live Pregnancy Due Date Calculator to your own website with this snippet — it loads the real, working calculator in an iframe.

<iframe src="https://nexlove.org/embed/pregnancy-due-date-calculator.html" width="100%" height="600" style="border:1px solid #e2e8f0;border-radius:12px" title="Pregnancy Due Date Calculator — NexLove.org" loading="lazy"></iframe>

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