Conception Date Due Date Calculator
Calculate your due date based on the conception date.
How is Due Date Calculated?
Naegele's Rule
The most common method for calculating your due date is Naegele's Rule, which adds 280 days (40 weeks) to the first day of your last menstrual period (LMP). This method assumes:
- Regular 28-day menstrual cycles
- Ovulation occurs on day 14
- Conception occurs within 24 hours of ovulation
Alternative Methods
- Conception Date: Add 266 days to the conception date
- IVF Transfer: Add 266 days to the embryo transfer date
- Ultrasound Dating: Based on fetal measurements and gestational age
Important Pregnancy Facts
Pregnancy Length
- 40 weeks (280 days) from LMP
- 38 weeks from conception
- Three trimesters of ~13 weeks each
Trimester Breakdown
- First: Weeks 1-13
- Second: Weeks 14-26
- Third: Weeks 27-40
Frequently Asked Questions
How accurate is the due date calculation?
Only about 5% of babies are born on their exact due date. The due date is an estimate, and normal births can occur between 38 and 42 weeks of pregnancy.
What if my cycles are irregular?
For irregular cycles, conception date or ultrasound dating may be more accurate. Try our conception calculator or ultrasound calculator.
When should I get my first ultrasound?
The first ultrasound is typically performed between weeks 8-14 of pregnancy. This early ultrasound provides the most accurate due date prediction.
Medical Disclaimer
This calculator provides estimations based on standard pregnancy durations. Every pregnancy is unique, and actual dates may vary. Always consult with your healthcare provider for personalized medical advice and accurate dating.
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About this Calculator
Calculate your due date based on the conception date.