Pregnancy Due Date Calculator & Calendar
Calculate your baby's due date and track your pregnancy week by week. See key milestones and trimesters. A helpful planner for expecting parents.
About Due Date Calculation
The due date is estimated using Naegele's rule (LMP + 280 days) or by adding 266 days to the conception date. Only about 5% of babies are born on their due date - most arrive within 2 weeks before or after. Always consult your healthcare provider for accurate dating.
How the Pregnancy Due Date Calculator Works
Choose your calculation method: Last Menstrual Period (LMP), conception date, or IVF transfer date. Each method uses medically-recognized formulas to estimate your due date.
For LMP calculations, the tool uses Naegele's rule - adding 280 days (40 weeks) to your last period's start date. It adjusts for cycle lengths different from the standard 28 days.
Conception date calculations add 266 days (38 weeks) from when the egg was fertilized. This method is more accurate if you know the exact conception date.
IVF calculations account for embryo age at transfer. Select 3-day or 5-day (blastocyst) embryo, and the tool adjusts the due date accordingly.
Results show your current week of pregnancy, trimester information, time remaining, and a visual progress bar. Key milestone dates are calculated automatically.
When You'd Actually Use This
Confirming doctor's due date
Double-check the date your healthcare provider gave you. Compare calculations from different methods. Feel confident in your timeline.
IVF pregnancy tracking
IVF pregnancies need different calculations. Input your transfer date and embryo age. Get an accurate due date specific to your treatment.
Irregular cycle adjustment
Standard calculators assume 28-day cycles. Adjust for your actual cycle length. Get a more personalized due date estimate.
Pregnancy announcement planning
Know your due date before sharing news. Plan announcements around milestones. "Coming [month/year]" becomes specific.
Baby shower scheduling
Plan events at the right time in pregnancy. Avoid scheduling too close to due date. Give guests plenty of notice.
Maternity leave planning
Coordinate time off with your due date. Notify employers with accurate timelines. Plan for early or late arrivals.
What to Know Before Using
Due dates are estimates, not deadlines.Only about 5% of babies arrive on their due date. Most are born within 2 weeks before or after. Your healthcare provider may adjust based on ultrasounds.
LMP method assumes regular cycles.If your cycles are irregular, the conception date method may be more accurate. Ultrasound dating is most precise in the first trimester.
IVF dates are typically most accurate.Since fertilization date is known precisely, IVF due dates have less variance. Still expect natural variation in actual delivery timing.
First trimester ultrasounds refine dating.Crown-rump length measurements between 8-13 weeks provide accurate dating. Your provider may adjust the calculated due date based on these scans.
Medical disclaimer: This calculator provides estimates only. Always consult your healthcare provider for medical advice and accurate dating. Ultrasound measurements are the gold standard.
Common Questions
Why is my due date different from my doctor's?
Doctors use ultrasound measurements, especially first-trimester scans, which are more accurate than LMP calculations. They may also round to the nearest week. Trust your provider's dating.
What if I don't know my cycle length?
Use the default 28 days. The difference is usually minimal - a few days at most. Early ultrasound will provide more accurate dating if needed.
Can the due date change?
The calculated date doesn't change, but your estimated delivery window might. Babies typically arrive within 2 weeks of the due date. First babies often arrive late.
How accurate is the conception date method?
Very accurate if you know the exact date. Ovulation predictor kits or fertility tracking apps can help identify conception. Sperm can live up to 5 days, so intercourse date isn't conception date.
What's a blastocyst transfer?
A blastocyst is a 5-6 day old embryo. Day 5 transfers are most common. The calculator subtracts these days from the standard 266-day conception-to-birth timeline.
When should I start prenatal care?
Contact your healthcare provider as soon as you suspect pregnancy. First prenatal visits typically occur around 8 weeks. Early care ensures healthy development.
What are trimesters?
Pregnancy is divided into three trimesters: First (weeks 1-12), Second (weeks 13-26), Third (weeks 27-40). Each has different developmental milestones and symptoms.
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