Due Date Calculator | Pregnancy Due Date & Timeline
Calculate your estimated due date based on last menstrual period, conception date, or IVF transfer. Track pregnancy week-by-week with detailed timeline.
The Due Date Calculator is a precise pregnancy tool that helps determine your estimated delivery date based on key milestones. Whether you know your last menstrual period, conception date, or IVF transfer date, this calculator provides accurate due date projections with detailed week-by-week pregnancy information.
How Pregnancy Due Dates Are Calculated
A typical pregnancy lasts approximately 280 days (40 weeks) from the first day of your last menstrual period (LMP). This calculation uses Naegele's Rule, which adds 280 days to the LMP. However, actual delivery dates can vary by about two weeks before or after the estimated due date.
Key Calculation Methods
Where:
LMP = First day of Last Menstrual Period
EDD = Estimated Due Date
280 days = Standard pregnancy duration (40 weeks)
Key Features
- Multiple Calculation Methods: Calculate based on LMP, conception date, IVF transfer date, or ultrasound measurements.
- Interactive Pregnancy Timeline: Visualize your entire pregnancy journey with week-by-week milestones.
- Trimester Breakdown: Detailed information about each trimester's development.
- Important Dates: Calculate key milestones like end of first trimester, viability week, and full-term dates.
- Fetal Development: Week-by-week fetal size comparisons with common fruits and vegetables.
- Mobile Responsive: Perfect for expecting parents to track progress on any device.
- Print & Share: Generate printable pregnancy calendars to share with family and healthcare providers.
Pregnancy Timeline Overview
First Trimester
Weeks 1-13: Critical development of baby's organs, brain, and spinal cord.
• Morning sickness common
• Fatigue and breast tenderness
• Heartbeat detectable
Second Trimester
Weeks 14-26: Rapid growth, movement felt, gender often detectable.
Third Trimester
Weeks 27-40: Final growth, lung development, preparation for birth.
• Increased discomfort
• Braxton Hicks contractions
• Baby drops into position
Common Calculation Methods
Calculation Options
- Last Menstrual Period (LMP): Most common method - Add 280 days to LMP
- Conception Date: Add 266 days to known conception date
- IVF Transfer: Add specific days based on embryo type (3-day or 5-day)
- Ultrasound Dating: Most accurate method using crown-rump length
- Current Pregnancy Week: Calculate backward from current week
Important Pregnancy Milestones
| Milestone | Weeks | Key Developments | Fetal Size |
|---|---|---|---|
| First Heartbeat | 5-6 weeks | Cardiac tissue begins pulsing | Sesame seed |
| End of First Trimester | 13 weeks | All organs formed, miscarriage risk decreases | Peach |
| Anatomy Scan | 18-22 weeks | Detailed organ check, gender visible | Mango |
| Viability | 24 weeks | Baby could survive with medical help | Corn |
| Full Term | 37 weeks | Lungs mature, ready for birth | Watermelon |
IVF & Assisted Reproduction
3-Day Embryo Transfer
- Transfer occurs 3 days after egg retrieval
- Add 263 days to transfer date
- Embryo has approximately 8 cells
- Due date is about 38 weeks from transfer
5-Day Blastocyst Transfer
- Transfer occurs 5 days after egg retrieval
- Add 261 days to transfer date
- Embryo has 70-100 cells
- Higher implantation success rate
Factors Affecting Due Date Accuracy
Menstrual Cycle Length
Women with longer cycles (>28 days) may ovulate later, requiring adjustment to due date calculation.
Irregular Periods
If periods are irregular, LMP-based calculations are less accurate. Ultrasound dating is recommended.
Multiple Pregnancies
Twins and multiples often deliver earlier, typically around 36-37 weeks rather than 40 weeks.
Important Medical Notes
- Only 5% of babies are born on their exact due date
- Delivery between 37-42 weeks is considered normal
- Always confirm due date with ultrasound measurement
- Report any bleeding, severe pain, or decreased fetal movement immediately
- Regular prenatal care is essential for healthy pregnancy
- Discuss any concerns with your healthcare provider
Frequently Asked Questions
How accurate is the due date calculation?
LMP-based calculations are accurate within ±2 weeks. Early ultrasound dating (8-12 weeks) is accurate within ±5 days. Third-trimester ultrasounds are least accurate (±3 weeks).
What if I don't remember my LMP?
Use conception date if known, or current pregnancy week. An early ultrasound is the most accurate alternative for dating the pregnancy.
Can my due date change?
Yes, healthcare providers may adjust your due date based on ultrasound measurements, especially if there's more than 7 days difference from LMP calculation.
What is considered full term?
37-40 weeks is full term. Early term is 37-38 weeks, full term is 39-40 weeks, and late term is 41-42 weeks. Post-term is after 42 weeks.
This due date calculator is intended for informational and educational purposes only. It should not be used as a substitute for professional medical advice, diagnosis, or treatment. Always consult with a qualified healthcare provider regarding any pregnancy-related questions or concerns. Actual delivery dates may vary based on individual circumstances, and only your healthcare provider can provide accurate medical guidance.