Due Date Calculator
Calculate your due date, current pregnancy week, trimester info, and key milestones based on your last menstrual period (LMP)
Enter the first day of your last menstrual period
💡 This calculator is for reference only. Consult your healthcare provider for accurate due date and pregnancy information. Calculations are based on Naegele's Rule.
📖 How to Use
- Enter the first day of your last menstrual period
- View your due date, current pregnancy week, and trimester info
- Check key milestones for upcoming appointments
- Use reverse calculation to estimate conception date
✨ Features
- ✓Due date calculation based on Naegele's Rule
- ✓Current pregnancy week and days display
- ✓Trimester information (1st/2nd/3rd)
- ✓Key milestones (12-week screening, 20-week anatomy scan, etc.)
- ✓Reverse calculation for conception date and fertile window
📐 Formula
Due Date = Last Menstrual Period + 280 days (40 weeks)
Conception ≈ Last Menstrual Period + 14 days💡 How It Works
- •Naegele's Rule calculates the due date by adding 280 days (40 weeks) to the last menstrual period (LMP).
- •Actual conception occurs around ovulation, typically about 14 days after LMP.
- •Pregnancy lasts about 38 weeks (266 days), but counting from LMP makes it 40 weeks.
- •1st Trimester (1-12 weeks): Major organ formation, morning sickness period
- •2nd Trimester (13-26 weeks): Stable period, feeling baby movements, gender determination
- •3rd Trimester (27-40 weeks): Baby growth completion, birth preparation
- •From 37 weeks, pregnancy is considered full-term and delivery is normal.
❓ FAQ
Q. How accurate is the due date?
A. The due date is an estimate. Most births occur within 2 weeks of the due date. Only about 5% of babies are born exactly on their due date.
Q. What if I don't know my last menstrual period?
A. An ultrasound can measure the baby's size to estimate pregnancy weeks and due date. Consult your healthcare provider for accurate assessment.
Q. What is a trimester?
A. Pregnancy is divided into three trimesters: 1st (1-12 weeks), 2nd (13-26 weeks), and 3rd (27-40 weeks). Each period has different fetal development and maternal symptoms.
Q. When is full term?
A. Pregnancy is considered full-term at 37 weeks. Birth before 37 weeks is preterm, and after 42 weeks is post-term.
Q. Is the conception date the same as intercourse date?
A. Not necessarily. Sperm can survive up to 5 days in the female body, so the intercourse date and actual conception date may differ. Conception occurs around ovulation.
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