Pregnancy Due Date Calculator
Estimate your due date from last period date.
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Estimated Due Date
How Is a Due Date Calculated?
A pregnancy due date is typically calculated using Naegele's Rule: add 280 days (40 weeks) to the first day of your last menstrual period (LMP). This standard method assumes a 28-day cycle and that ovulation occurs on day 14. Only about 5% of babies are born exactly on their due date, but knowing your estimated date helps you and your healthcare provider plan effectively.
How to Use This Calculator
- Enter the first day of your last menstrual period (LMP).
- Click "Calculate" to see your estimated due date.
Key Pregnancy Milestones
| Week | Milestone |
|---|---|
| Week 4–5 | Positive pregnancy test possible |
| Week 8–10 | First prenatal appointment |
| Week 12 | End of first trimester, risk of miscarriage decreases |
| Week 18–20 | Anatomy ultrasound, possible gender reveal |
| Week 28 | Start of third trimester |
| Week 37–40 | Full term — baby is ready |
💡 Note: Your doctor may adjust your due date after an early ultrasound, which is often more accurate than LMP calculation. Always rely on your healthcare provider for your official due date.
⚠️ This calculator provides an estimate only. Always consult your doctor or midwife for accurate pregnancy dating and medical guidance.