Pregnancy Due Date Calculator
Calculate your due date, pregnancy week, trimester, and days until delivery from LMP or conception date.
Pregnancy Due Date Calculator
Pregnancy Details
Enter LMP or conception date for due date & gestational age
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Key weeks in your pregnancy journey.
Trimester Guide
Where you are in your pregnancy.
Health Insights
Personalized takeaways from your numbers.
Real-Life Examples
LMP ~12 weeks ago
20 weeks pregnant
The Formula Behind It
Due Date = LMP + 280 days (Naegele's Rule)Variables
- Due Date = LMP + 280 days
- Conception: Due = Date + 266 days
How It Works
- Choose calculation method — Last Menstrual Period (LMP) or conception date.
- Enter the first day of your last period or conception date.
- Adjust cycle length if different from 28 days (LMP method only).
- View due date, gestational age in weeks and days, trimester, and days remaining.
About Pregnancy Due Date Calculator
The Pregnancy Due Date Calculator estimates your expected delivery date and current gestational age using standard obstetric formulas. Whether you know your last menstrual period (LMP) or conception date, this tool provides an instant timeline for planning prenatal care and tracking milestones.
How Due Dates Are Calculated
The most common method is Naegele’s rule: add 280 days (40 weeks) to the first day of your last menstrual period. If your menstrual cycle is longer or shorter than 28 days, we adjust accordingly. When using conception date, we add 266 days (38 weeks) since gestational age is counted from LMP, approximately two weeks before conception.
Understanding Gestational Age
Gestational age is expressed in weeks and days — for example, “12 weeks, 3 days” means you are in your 13th week of pregnancy. The first trimester spans weeks 1–12, the second trimester weeks 13–27, and the third trimester weeks 28 until delivery.
Important Medical Disclaimer
Only about 5% of babies are born on the exact due date. Early ultrasound dating (dating scan at 8–12 weeks) is more accurate than LMP alone. This calculator is for informational purposes — always follow guidance from your obstetrician, midwife, or healthcare provider for prenatal care and delivery planning.
Frequently Asked Questions
How is my due date calculated?
From your last menstrual period (LMP), due date is typically LMP + 280 days (40 weeks). From conception, due date is conception + 266 days.
What is Naegele's rule?
Add 1 year, subtract 3 months, and add 7 days to the first day of your LMP. This equals approximately 280 days from LMP.
How accurate is a due date calculator?
Only about 5% of babies are born on the exact due date. Most arrive within two weeks before or after. Ultrasound dating is more precise in early pregnancy.
What trimester am I in?
First trimester is weeks 1–12, second is weeks 13–27, and third is weeks 28 until delivery.
Can I use conception date instead of LMP?
Yes. Select conception date mode — we add 266 days (38 weeks) to estimate your due date.
Does cycle length affect due date?
Yes. If your cycle is longer or shorter than 28 days, we adjust the due date accordingly.
When should I see a doctor?
Schedule a prenatal visit as soon as you know you're pregnant. This calculator is informational only — not medical advice.
What if I had IVF?
IVF due dates are set by your clinic based on embryo transfer date. Use conception/transfer date mode with guidance from your provider.
How many weeks pregnant am I?
Gestational age is counted from the first day of your LMP — the same start point used for due date calculation.
Is this calculator a substitute for ultrasound?
No. Early ultrasound (dating scan) is the most accurate method. Always follow your healthcare provider's assessment.
Community Stories
Real experiences from people like you.
"Tracked weekly milestones with this calculator."
Stayed informed through all three trimesters